The reason I haven't been posting... well, okay there are a few reasons: first, I am now grinding in all my free time; second, I started going to the gym (again) about three weeks ago right after work, so I don't get home and done making/eating dinner and cleaning the dishes until around 7pm (which doesn't leave much time for grinding given that I wake up at 6:30 >_<); third, I have been extremely busy at work, so posting during the day is difficult as well; and fourth, it is the holiday season and in such fashions my girlfriend and I have been attending and throwing a number of parties and shopping and whatever-else during most of my free time. I think (read: hope) that after I hit 85 and plow through some BGs for honor gear and what-not the holiday party scene will have died down a bit and my schedule will become a bit more regular meaning I can actually fit in an hour to compose a post (usually it takes that long; today it will take 15m because that is what I have).

Today, I want to talk about gemming. First things first, however: Rake is bugged at the moment. Rake is ticking for me (81) for around 10k (crits) on mobs and closer to 6k (crit) on players. I do not expect this to remain permanently. That being said, Mastery is still by far and large our best stat against targets who can live longer than 10 seconds (for grinding I would still very much suggest stacking agility until you are blue in the face). It is important to note, however, that agility is ALMOST as good as Mastery, so you will not want to end up skipping socket bonuses for the most part.

Yellow - Mastery
Blue - Hit (to cap); Spell Pen (to cap); Stam+Mastery (green gem)
Red - Agility

Easy-peazy, right? If you cannot meet the hit and spell-pen caps via solid colored gems, replace red gems with purple gems of agility+hit/pen. The reason for this is as I explained before as Mastery is just the stronger of the two.

I would also like to point out that there exists a piece of PvP gear (shoulders) with expertise on it... I know that this is stupid, but I petitioned against it while on beta pretty vigorously and Blizzard did not seem to care at all. Reforge as much of it as you can to Mastery. Also, as far as my testing went on the Beta, the PvP Gloves do NOT have a bonus attributed to them, and if that remains true into S9, consider using your Wrathful Gloves instead; the stats are a lot lower, but that reduced cost to Skull Bash is imperative.

EDIT:

Oh... here's another thing that's been bothering me: people are already talking about how we are going to have "less critical strike chance in PvP" in Cataclysm because we will be reforging everything to Mastery. First off, this is simply wrong for the reason of not being able to reforge ALL our critical strike rating to Mastery, only a small piece of it and only if that piece of gear does not already have Mastery; second off, we still stack agility pretty hard and that aids our critical strike rating rather directly; and third, even if we are walking around with 30% critical strike chance, that is actually MORE than most Ferals had effectively in PvP settings in Wrath since Resilience USED TO reduce your chance to strike critically by as much as 15% (and most PvP Ferals were rocking 45% crit in full Wrathful), but it does not any more... so effectively we should have roughly the same effective critical strike chance in Cataclysm that we did in Wrath.

I think it's that resilience bit that keeps getting people. There is definitely going to be some lowered critical strike chances in the PvE environments, but that's a good thing in my opinion. Ferals were (arguably still are) too dependent upon critical strikes for building combo points to use our finishers, but in Cataclysm we seem to have enough critical strike chance to build our finishers in a good amount of time and keep them up long enough to land more. Additionally, we have more cooldowns to use and our damage is spread more amongst our bleeds than our direct damage abilities, so it will matter less about Shredding and more about Ripping/Raking (and they're our two least expensive and best damage-dealing abilities).