You can buzz from outside gmail (in a new tab) using the mobile version directly on a pc browser. The following links open Buzz in view mode and compose mode.
The compose mode is capable of geo localization based on browser feature (but it’s not precise as on a mobile device). Try it out by your own.
Buzz in compose mode like on mobile:
https://m.google.com/app/buzz?force=1#~buzz:sv=me&view=compose
Buzz in view mode like on mobile:
https://m.google.com/app/buzz?force=1#~buzz:view=me