If you have an Edge 500 or 800 think twice before you upgrade your firmware to 3.0. Looking at the Garmin forums, I am not alone in having serious problems with it. To be more specific, Garmin Connect will no longer upload your fit files, and for Powertap users, Power Agent will not accept the fit files recorded under firmware 3.0.
For now, I've gone back to firmware 2.8 which was working fine for me. Anyone who has worked through this problem and solved it, feel free to chime in.