I think this heavily depends on what kind of software you are using with an Intel Mac. I don't see Rosetta as an all-around solution to the problem... During the OS 9 to OS X transition, classic was touted as being able to run all your programs in OS X. Unfortunately most of the pro audio and pro video applications that I was interested in running didn't run well under classic (if at all). I see Rosetta as the same kind of stop-gap solution. They will run simple applications (which is fine for the majority of users) like Microsoft Office, but when it comes to CPU intensive video and audio applications, Rosetta will be less than helpful. So I guess this depends on what kind of applications you are planning on using with one of those new Intel macs.
Personally, I use a lot of esoteric synthesis programs like SuperCollider and Max/MSP which aren't going to run well under Rosetta (I can almost guarantee this fact, as the developers of this software have said not to expect dual binaries for a while). I can imagine that dual binaries for these programs are also a long ways off (1-2 years).
Even if you have all the speed in the world, there's going to be a bottleneck effect if you can't run the applications you need on the new platform. I just purchased a PowerBook G4 to last me through the software/hardware transition, and I hope to buy an intel mac after all the applications I need are ported and native to the new intel format. However like the rest of you, I'm excited to see what the new Macs will look like!