If you need it now, buy.
Apple can be secretive, and given the news of a new case design in 2012, along with Ivy Bridge, I doubt anything will come out until then.
If they do a refresh, it'd be minor. The mid-2009 refresh had better specs and better monitor panel technology. I don't see that for any mid- or late-2011 design.
But 2012 will be.
I can say this: My 2011 17" MBP runs far faster than the 2009 17" MBP I had sold a month ago, and doesn't get as hot under the same level of use.
2011 MBP temps @ 3000RPM: Photoshop moderate use = 46C (probably wouldn't get over 52C under heavy use), Dreamweaver = 40C, web browsing = 37C... Windows + UT2004 in Parallels = <70C (often 66C). Poser 2010 render (10,000x10,000 DPI) = 89C. Haven't done Flash in a while and there's one game I want to port to the iPad, so I'll have temp results for this in the future at some point... but it won't get up to 99C, of that I'm more than certain...
2009 MBP temps @ 3000RPM: Photoshop heavy use/painting = 79C, web browsing = 44C, Flash actionscript compiling = 99C

, Windows + UT2004 in Parallels = 82C.