There has almost certainly been more than one stig for a few years now, Ben collins may have been the main stig but a few other drivers have donned the costume at other times to either cover when Ben wasn't available or for some of the more specialist features where he either couldn't do it or wasn't allowed to drive the car. for example the snow mobile jump was almost certainly Dan Lang (a Swedish snowmobile crosser) and the F1 car that was put round the track was almost certainly Heikki Kovalainen (who was signed to Renault at the time, does any one really think Renault would let anyone other than their own drivers drive one of their F1 cars?)
Julian Bailey is another driver that has been speculated to have stood in for the stig on occasions and that's were my money would currently be.
I think that it is Tiff Needell. Look carefully at his body profile beneath the white suit and the height. He is used to the track and took that Atom round like an Appollo rocket.
Rumour has it that it's a woman, German racing driver Sabine Schmitz, the lady who guided Jeremy around the Nurburgring a few years back when he was trying to break the record (failed of course!).
I heard the woman thing as well but when you look when the Stig takes the Atom round the track, there doesn't apper to be any boobs, either that or she hasn't got any.
I think its Needell, he raced the motorbike and all James May said was thanks Tiff considering hes quite the celebrity in motoring circles I thought it was strangley low key.
However no doubt Top Gear love to lay down a few false trails and throw in a few red herrings.