The switch to intel (and new iMacs accordingly) happened maybe a month after I bought a PPC iSight iMac. I needed it right then and there though so I couldn't wait around just in case an update came. When it did, you bet I was gutted but these things happen.
I got a newly updated G5 iMac about 6 weeks before the keynote announcing the Intel switch. IIRC, the general consensus on this forum was that it was a "sweet spot" good price-to-feature buy.
We've all gotten burned at some point. Like the poster says, it happens.