Currently when new files are synced into the owncloud folder a balloon popup is shown (at least it is, on the Windows client).
It would be extremely useful if clicking on this popup took you to the folder where the files have just been synced.
Furthermore, left clicking on the tray icon shows the owncloud settings interface. I can't imagine many users want to access this, especially after the initial configuration of adding accounts/sync folders set-up is completed.
I think it'd make more sense if a left click would bring up the owncloud folder versus the interface. Right clicking should still make the context menu pop up with all the options in there (same as now).