First Two Weeks, Thursday

Flashforward (ABC)
Sampling: It led off the night with a 4.0 demo, which is really good, period.
Retention: A 3.7 in week two means an encouraging 8% drop. This is a preliminary vs. final comparison so it may go up a bit (FF dropped in finals last week) but still, not bad at all.
Prognosis: Critics seem relatively positive in general, and both the sampling and retention numbers are nice. This one's probably going to be around for at least this season.

Community (NBC)
Sampling: The premiere had a 3.8 demo, which in NBC terms is like a miracle from above. It had a big The Office lead-in but retained over 90% of it. That's an incredibly good start.
Retention: Ugly. The drop in week 2 was to a 2.7 demo. That's a really hefty 29% fall. Extremely bad news. However, it stayed steady in week 3, which is a bit of a surprise for a show that takes that kind of week 2 dive.
Prognosis: The ultimate collision of great sampling and bad retention. Week 3 retention was a step in the right direction, but next week comes a move to 8pm and a "true test" of just how loyal this audience is. Difficult to make a prognosis here until we see what happens at 8, but so far it's a pretty mixed bag. I'd bank on a back nine right now simply because upper-2s is still very good as NBC goes.

The Vampire Diaries (CW)
Sampling: The premiere was monstrous for the CW, scoring a network-high 4.91 million viewers, 2.1 A18-49, and 3.1 in the "CW demo" of women 18-34. This was comparable to the breakout start of 90210 last year.
Retention: The week 2 crash was also comparable, dropping over a million of those viewers right off the bat. However, its fall to a 2.6 in the CW demo meant an average-ish 16% drop, which is nothing horrific, and it's stayed right in that 2.6 or 2.7 area the next couple weeks, which is very encouraging.
Prognosis: A lot of the traditionally reported numbers make TVD look really good. In total viewers and adults 18-49 it's basically the flagship show of the network. But the mid to upper 2's in W18-34 are not quite as dominant; Gossip Girl often breaks 3 in that. Still, this thing's not going away this season and almost certainly sticking around for next season. You can book that.