How can I browse windows shares from unity?
The only way I've found out how to do this is to open a folder window from Unity and then find it from there. Go to Files and Folders on the launcher on the left, and open any folder window (ie, Documents). If it doesn't open in the file manager, hit the little folder icon on the top-right. You should then see the classic file manager appear. Open the Go menu and select Network. From there you can browse Windows shares.
If you already have the file manager pinned to your launcher, you can also open it there.
So, in short, I don't think you can currently do this from within Unity. Whether this will be a feature for 11.04 remains to be seen.