Matt Smith. An unknown British actor. Here is a link to his IMDB page. http://www.imdb.com/name/nm1741002/
Well, he's played against Billie Piper in "Ruby in the smoke"... Tennant has been a great Doctor, so as sad I am to see him go, I'm eager to see this new one...
Yeah...I came late to the game, Eccleston was my first doctor. I loved him, very intense, but Tennant has been fantastic. I'm worried about this new guy, but hey--change can be good!
Davison can still be heard as The Doctor in the Big Finish audio adventures: http://www.bigfinish.com/
I recomend: http://www.bigfinish.com/34-Doctor-Who-Spare-Parts It's one of the best Big Finish adventures, in good competiotion with: http://www.bigfinish.com/58-Doctor-Who-The-Harvest (McCoy, but it's great!) 2 great ones to get you started!
There's no "season" as such this year. There are going to be 4 specials with David Tennant, and then the next season in 2010 will be with the new kid.