If it's not broken, it doesn't have enough features yet
is the 'pin tab on taskbar' feature (if you have Win7). My company blocks access to GMail, so I have to use the web interface -- now I can have GMail in its own 'application' on the taskbar next to Outlook
And yes, I am aware of the Firefox 4 'application tabs' feature -- I've been using my GMail that way ever since I started using the FF4 beta.
Now time will tell which solution fits my needs best.
Quark! Quark! Beware the quantum duck!