The only thing holding me back from upgrading to Lion is the loss of Rosetta. You must realize that that is huge for some. For me, it would mean I would have to shell out $200 to Intuit to upgrade from QuickBooks 2007 which works just fine in Snow Leopard. I also have a couple other PPC-code apps which would not run under Lion on my MacBook Pro 17".
I actually don't mind jumping back to an older Mac once in a while. For example, I have an old version of BarCodePro which runs in Mac Classic OS 9 on my G4 PPC/500 MHz/1 GB SDRAM tower (which still provides daily service as my design jobs file server). I fire up Classic about 2 or 3 times a year to do a few bar codes. That has saved me the cost of upgrading my bar code program – minimum $200.
I also recently purchased a used PowerPC G5 tower ("stuck" at Leopard) for $200 which is being groomed now to replace my PowerPC G4 as my file server. I am doing nightly backups using Bombich's Carbon Copy Cloner, finally got an error-free clone last night (thanks to guidance by Mike Bombich) and am ready now to cut over.
There is a lot of legacy Mac equipment and software which is still proving itself to be very useful to media designers like me.