To be honest if I clicked on a link in a "GMail app" I'd expect it to open a new "full" browser window (or a new tab in an existing browser window). You'd have to be able to distinguish between internal and external links, of course, but the domain name is a workable heuristic.
The ability to open new tabs should probably be configured on an app-by-app basis. Opening tabs of mail is a pretty sensible idea, but a game developer using HTML5 would likely want to prevent that. Ditto the location bar. (I agree that the user should be able to override these settings.)
I would want a external link in the gmail app, to open in a tab in the gmail app.
The internet is everywhere.. I dont want those 50 tabs in one big browser window, nor do i want them in separate windows.
I want them organised based on context. Most of those tabs belong to the initiating application. From a hackers news app, with the chosen articles, to a google docs app, with open documents.
As long as i can pick up a tab, and add it to some other window, that would make the most sense to me.
The ability to open new tabs should probably be configured on an app-by-app basis. Opening tabs of mail is a pretty sensible idea, but a game developer using HTML5 would likely want to prevent that. Ditto the location bar. (I agree that the user should be able to override these settings.)