All Leopard installations fine here: MacBook, PowerMac G5 and MacMini G4 (the iBook won't run it, sadly). All seemed to go fairly swiftly, around 30-40 minutes (I didn't install the "foreign" language sets). Have activated Time Machine on the G5 and the initial data transfer was 140Gb (!). We'll see how useful it proves. All three machines seem to work a little quicker (as per every other upgrade I've done on the Mac). The new "Quick Look" feature in the Finder is already invaluable for me, although I wish it was available as a right-click item. Ho-hum.
Only a couple of glitches: my company's rostering webpage won't work with Safari 3.0.4, yet worked fine with 3.0.3, and still works fine with Firefox. I suspect there will be an update in due course. The other problem was that it seemed to erase any knowledge of Aperture on the G5 having a serial number. This isn't a major problem as it's a kosher copy – it's just that we moved house last week and I can't find the original box and serial number!
AppleMacster