If you're gonna wait on the 990X (speed bump of the 980X IIRC), might as well wait a bit longer for the Sandy Bridge. My understanding is that there will be an 8-core, 16 thread version at hopefully the $1K benchmark price. Since SB seems to have about a 20% IPC boost over Westmere, that and the two extra cores should make for a big boost in multithreaded stuff. For gaming, you'd be better off upgrading your GPU.
The 8 cores dont come until the end of next year to my knowledge, ivy bridge 22nm die shrink. SB this year into Q1 2011 will max at 4C/8T, and the 990x is the top of their charts until IB.