This news may seem a little old to some people, but it's better than nothing. Anyway, rumours have been circulating that Series 5, where Matt Smith makes his debut as the Doctor, is set to be split into two halves - 6 episodes in the spring featuring a cliffhanger, and then the other 7 episodes later on in the year. This is a US style approach to the series, and I don't think it would work, although nothing has been confirmed yet.
Also, while posting this I realised that Matt Smith has an oddly long neck... not that I've got anything against that, I'm just being over-observant!
Thanks to Life, Doctor Who & Combom for this!