5D MK II question
The Mark II was announced circa September 2008 and became available around November that year. Since the xD series have had an update schedule of approximately 3 years, I wouldn't look for a Mark III announcement for at least another year yet.
But then again, Canon has been known to pull some surprises on us now and then.
If you go to:
you can see the release dates of Canon DSLRs over the years for yourself.