I'd recommend waiting for the 2012 refresh and here's why:
1) Apple’s next Macbook Pro refresh is likely to include Intel’s forthcoming CPU bump codenamed Ivy Bridge (scheduled to debut in Q4 2011) which, if Intel meets their goals, will have 20% better performance, use slightly less power and have a considerably more favorable TDP rating (less thermal output).
And in 2013, there will be even better chips. If you're willing to wait a year, you're willing to wait forever
2) Intel’s integrated graphics will no doubt improve somewhat. I doubt it will be enough of an advancement to merit the outright removal of the discrete GPU from the higher-end MacBook Pros, but it could be enough to raise the cross-over threshold where the discrete GPU takes over, which would have a positive impact on battery life and net thermal output in several use cases.
Besides games, I think the Intel HD 3000 GPU can handle just about anything you throw at it
3) OS X 10.7, codenamed Lion will have been released, as likely will the inevitable first service release that resolves some of Lion’s must-fix RTM bugs. Somewhere in this mix will likely exist improved graphics drivers.
Likely any purchase made in the next month or two will be eligible for Apple's $9.99 upgrade to Lion. And heck, you'd rather want to have an OS with a tried and tested version of OS X (aka Snow Leopard) while Lion works out it's kinks and developers update their software.
4) Maturing SSD technology may finally put SSD upgrades at a point of mainstream accessibility. Right now, the benefits don't always match the costs. Apple may also include TRIM support for non-Apple-supplied SSDs when Lion ships.
While technology may be "mainstream accessible", it has always been cheaper to buy parts and upgrade them yourself.
5) There will be a much clearer picture of where Thunderbolt stands.
This port will still exist for use in 2011 MBPs
6) From a driver perspective, it appears Apple still has room to improve with the new hardware.
Hardware can always be improved
7) Most builds of the 2011 MBP are showing considerable depreciation in the secondary markets, so you might not be able trade up for next year's model without digging deeply into your own pocket.
So buy from the secondary market instead of from Apple. I got a new high-end 2011 15" MacBook Pro from eBay for only $1815 shipped. At that price, it was a steal. After tax, it was a savings of $565. I hardly think they'd depreciate enough that that same notebook next year will be worth significantly less.
