As I've noted before, the issue with HTTPS is not one of server cost any more. However, I am aware of several Google services that are not available over HTTPS. Maps and AdSense are the ones which I'm familiar with and, if people are having issues with others, please let me know.
Google is a large company and I can't speak for the Maps nor AdSense teams. They have their own developer relations folks who know far more about their systems than I ever will, but I have chatted with them previously and they are aware of the issue.
In general, Google supports the use of HTTPS [1] and I hope that we can get to the point where it's more widespread.
http://googleblog.blogspot.com/2010/05/search-more-securely-...