When Google Buzz was recently launched, I was rather sad because I wasn't able to use it. It's currently only available from GMail (not from Google Mail on my fuxoft.cz domain, hosted by Google). I also have standard Google account for the same e-mail (firstname.lastname@example.org) so that I can log into Google Reader or Google Maps, but this was also no help because you cannot have GMail for an account that doesn't end with "@gmail.com" (obviously).
However, I was able to access Buzz using my Android phone's browser (NOT using the Buzz mobile app), by simply visiting m.google.com/app/buzz anc clicking "Continue on an usupported browser". I was then able to see the Buzz posts of my Friends and post my own. Even the geolocation and mini-maps were working (although there are probably many other features I cannot access at all, e.g. linking Buzz to different services).
This method also works with standard PC browser, providing you the way (although not very elegant) to access Google Buzz if your Google account is not @gmail.com - just visit m.google.com/app/buzz from your standard desktop browser!
Disclaimer: I am not sure if I somehow discovered "a shape of things to come" or if this is a bug. I am also a little nervous because I am not sure what information is taken from which of my two "email@example.com" accounts...