A much more sensible format in my opinion, 1 hour weekly shows for the duration of Autumn.

Autumnwatch 2009
Fri 2nd October - Fri 20th November
9-10pm every Friday night on BBC TWO
(followed by Autumnwatch Unsprung 10-10.30pm on BBC TWO, plus
a repeat of the main show for family viewing on Saturday afternoons on BBC TWO)... and across the BBC on regional TV, local radio, on the web... and where you live