Nice little video on how to Speed up your iOS 4 iPhone 3G and iPod touch 2G. Corresponds nicely with the reports that Apple is looking into the issues with iOS4 on a 3G iPhone.

As a spoiler the tip is "disable spotlight search for anything that you don't use". Will see how it works soon. As an Apple fanboy I have to say that the fact they allowed iOS4 on the 3G was a big mistake, even disabling multi-tasking and wallpapers. Right now my phone is painfully slow, and if I was a non-fanboy/normal user/unsuspecting moggle, it's an experience I wouldn't be happy with, and I'd be bitching about Apple selling crappy hardware (2 generations old or not).

Note: The comments seem to indicate this isn't going to do anything at all, though maybe a short term benefit could be from the act of the reboot clearing out the OS and memory.