We are currently working on the iPad app icon for SalesChamp, an iPad application for sales professionals, and we don't know whether we should put a border around the app icon or not.
This is the official (full) logo:
These are the options for the homescreen we are thinking about:
As you can see the main difference is the presence of a border. Personally I like the bordered one more because it 'feels' more like an app and the border is also an important element in the full logo. Thirdly, it also combines better with a lighter background photo (as is also recommended in the iOS HIG).
However, a common argument against that logo is the feeling that the sales guy is getting 'boxed in', but the same argument can be made against the full logo.
Therefor I'm asking the wise UX community: should this app icon have a border?