The processor speed wouldn't be too noticeable, less than 10% faster, but the extra 128MB of SDRAM will pack a very noticeable punch.
Like others have said though, now is not the time to buy a MacBook Pro. I mean, unless you need to have it now, then of course now is the time.
Just keep in mind that the last full release was around June of last year, with an added 2.6GHz option landing early last fall. So it's just about time for some sort of revision.