The scary list - the one that has all conquest, valor, heroism and triumph loot - is coming.
As before, the gearing list is based on FeralByNight's system of weighing. Keep in mind that this is very, very dependent on other stats; do not use these values without understanding why they're good, and what to do if you don't have a ton of armor pen. In general a good rule of thumb is to use armor pen whenever the gear isn't going to be shared, and use agility whenever it is. If you don't have grim toll or mjolnir runestone, armor pen isn't as valuable as agility - but it doesn't really change these rankings at all.
The tier gear question is a lot more interesting this time around. The 2pT9 bonus is pretty good, though it's not as good as the insanely great 2pT8 bonus is. The estimates I've seen value the bonus at around 50-100 DPS, given that it's basically giving you a free shred while keeping higher rake uptimes up. The 4pT9 bonus is not nearly as sexy, by comparison. Ferocious Bites are a very small amount of overall DPS, even with higher gearing. 5% more crits on rips is very good, but it's not as good as the 2pT8 bonus or even the 4pT8 bonus, so realistically you should only break 2pT8 if you're getting a significant upgrade in the item quality.
Now, another interesting facet here is that because the gear is becoming better 'itemized' for rogues, it's becoming much better for cats and much worse for bears per item point. This is why, for example, hardmode Ulduar gear is so great compared to hardmode Coliseum gear for bears. The flip side of this is that cats are just getting more and more awesome.
If you want a summary of what to aim for, here goes:
For the Ulduar-25 raider who's got everything: Get the Ring, the Idol and the Hood. Don't bother getting T9.10 gear at all, as you'll likely get 2pT9.25 soon enough.
For the U-10 or lower U-25 geared cat: get the ring for sure. Get the Duskstalker shoulders. Get your T8.25 head and chest, then get T9.10 legs and gloves. If you're really wanting to push your DPS, go for the Hood of Lethal Intent first.
For heroic-gearing cats only:Get the ring first, then the duskstalker, shoulders, then the idol. Get the T8.25 head and chest as the biggest priority. Get the leggings of wavering shadow, and then get the T9.10 gloves - and maybe consider the T9.10 legs if you're running a lot of heroics. But since you're so starved for Triumph badges, the best upgrade by far is that ring.
- Dexterous Brightstone (35 emblems) - This currently ranks as the second-best ring in the Coliseum, second only to a hardmode drop. While the loot lists are clearly incomplete, that doesn't stop this from always being great - it's about 5 points higher than the best ring from Ulduar save the quest rewards from Algalon. Because it's so cheap and because it should remain best in slot or close to it for a while, and that rings are traditionally hard to come by since so many other classes need them, I'm recommending this as the best thing to get early on. Of course, if you have two awesome rings disregard. :)
- Hood of Lethal Intent (75 emblems). Remember where I said this was more of a cat item? Well, here it is. This is actually better than the T9.25 piece due to having hit and armor pen instead of crit and expertise, and all the other stats are identical. The reason this isn't quite as high is because of the expense, but make no mistake - this is 11 points higher than the Ulduar equivalent, and it will be an excellent upgrade for a while. It's also only a couple points worse than the hardmode T9.25 gear, again thanks to having armor pen and hit over expertise and crit. Definitely a good choice.
- Duskstalker Shoulderpads (45 emblems). These are about a 7-point upgrade from the bset non-hardmode item in Ulduar, and a couple points better than Shoulderpads of the Intruder. They are almost identical to the T9.25 shoulders as well; they trade haste for crit. Personally I find crit to be better, but FbN values haste slightly more. In nay case, they're both very close, and because they're so cheap and require no Trophy of the Crusade, they should be a high priority for most cats.
- Idol of Mutilation (25 emblems). Unlike the data for bears, this is a great idol for cats; Rawr has this as about an 100 DPS upgrade over Idol of Worship, assuming that the 200 agility is essentially up all the time. Given that it lasts for 16 seconds and that it triggers off of shreds and mangles, I suspect that's right. This isn't as high a priority because simply other items give a bigger bang for your buck, but if you're hurting on an idol it's hard to go wrong here.
- Runetotem's Shoulderpads of Conquest (30 emblems) - These are a fairly reasonable upgrade from T8.25 shoulders (3 points) and just barely below Shoulderpads of the Intruder. They're also quite cheap. If you desperately want to have 2pT8 + 2pT9 right away, this is a good spot to have. It's up to you whether the tier bonus and look is worth the slight downgrade from Duskstalker's.
- Runetotem's Handgrips of conquest (30 emblems) - These are a slight upgrade from the T8.25 gear, (about .75 points), and are loaded with hit, making these possibly somewhat awkward to use. They're not a huge upgrade but are fairly cheap, and could be a decent spot to go 2pT9 if you've got good options in other slots.
- Runetotem's Legguards of Conquest (50 emblems) - while these are a raw upgrade over the T8.25 item, they're not that great. Why? Because for Emblems of Conquest you can get the Leggings of Wavering Shadow instead, which are .08 points worse than these. Between the high cost and the alternatives that are available, the only reason to get these is because you really want a 2pT9 bonus.
- Runetotem's Headguard of Conquest (50 emblems) - not a good choice at all. They're a small (1 point) upgrade over T8.25, but because of the excellence of Hood of Lethal Intent, they get marked way, way down. Since you can get T8.25 via emblems of conquest, these become even worse. They're also not well-itemized to begin with. A poor choice to upgrade overall.
- Runetotem's rainments of conquest (50 emblems) - A decent upgrade over the T8.25 chest, but not an upgrade over a number of other Ulduar items like Winter's Icy Embrace. Still you should consider getting T8.25 with conquest badges anyway and do this later.
- Shard of the Crystal Heart (5o emblems) - this one was tough. With the huge amount of hit, chances are you'd go over the hitcap on this. But it's otherwise great as far as trinkets go, and if you've gotten unlucky with trinkets it may be worth it to you. For me sampling this in Rawr, it looks like it's significantly below Mirror of Truth and DM:G, much less something like Mjolnir. And that's with all of the hit being useful; if it's not, then it's even worse. I'd skip it and go for those two instead if at all possible. If you're curious, the Mark of Supremacy is similar.