If you Google this you wil find out that current white suited Stig is {usually} a racing driver called Ben Collins. He has competed in F3 and NASCAR among other things. The previous black suited Stig was ex Le-Mans driver Perry McCarthy but was "let go" for revealing the fact he was The Stig.
Ben isn't always The Stig though, sometimes the manufacturer doesn't let him do the job and they dress up their own guy (like Luca Badoa for Ferrari) instead.
The Stig is hot! I think he is someone we've never heard of and a new racer to the track. I went to see Top Gear and The Stig came and sat down - he is around 6 foot and has some pale-ish-tan skin poking out from under his helmet - SO HOT! ;)
Believe me or don't, the choice is yours. PErsonally I couldn't care less.
My brother-in-law is a LCM (lighting camerman) down at Dunsfold for the filming of TG. 70-75% of the time it is Ben, the rest of the time it's the manufacturers test driver (like Luca) or sometimes Darren Turner if Ben is away racing. Ben was quoted in the H&S report concerning Hamster's crash as well.