[smakz]

I've also heard rumors that Gmail and Adsense for Content aren't particularly profitable for Google. Of course I've also heard that the brand equity created with Gmail is very valuable and those two are extreme examples, but even based on similar rumors it's possible Google could shut down either one.

[joezydeco]

I don't think Gmail would get shut down since it's a part of Google Apps, a paid service. Unless that turns out to be a burden on the company...

[robk]

Adsense for Content is exceptionally profitable. Gmail pulls its weight.