Cliff notes:
Don't bother waiting. Get a g0 q6600 now.
**********************************
The q9450 isn't going to be released for awhile...
It's 45nm, so it will run cooler, which means it will overclock nicely as well...but so far all the Q9450 engineering samples we've seen have had FSB walls around 450-460fsb.
The new 45nm processors are about 5% faster than the current 65nm on average, which means if you hit the FSB wall at 450mhz you'll have 3.6ghz...which is comparable to a Q6600 @ approximately 3.8ghz.
So, regarding the 45nm:
Pros:
-Cooler, will most likely OC to 3.4+ghz without a hitch on air
-As far as we have seen, limited to ~ 3.6ghz
-Faster than the 65nm processors clock for clock
Cons:
-Waiting for release, which has now been delayed
-A bit pricey
-You can get a q6600 g0 RIGHT NOW for a good price....they still do 3.4+ghz at least on air...most likely more.