According to a website that I have found -
Series 3
to continue 8th June 2008
on ITV2 according to what's on tv magazine 9pm on ITV2.
September 10, 2009
it starts on itv2 on 25th January 2009
It is very far behind in the series to be on season 3, however, it is avaliable online.
Supernatural VII Starts on Monday 28 May at 20:30 on M-NET SERIES.
starts Sunday 27th Jan at 9.15pm on itv 2
The first half of the series will start on April 23rd, the other half will start in September.
April
Doctor Who series 6 will start on the 23rd April 2011, with 'The Impossible Astronaut' :)
April 24, 2008
series 5 finished December and continued again in April, so I'm guessing it will be around that time scale again. although season 6 finished October, so perhaps it will start a few months earlier
April 3rd
12th April