Tennant has not been confirmed for the 5th Season though - but then it is some time away!
It'll be interesting to see if Torchwood and The Sarah Jane Adventures continue through the 2009 schedule to keep the Whoverse a regular fixture on our screens.
BBC Reveals Doctor Who 'Gap Year' (BBC News Online; Monday 3rd September 2007)
In other news I think I have been infected with a time virus. I keep thinking that I'm in (and writing down on forms) 2008! I've been like this all day!