ugh, cos md5 squared is twice as secure as just once - why not md5 x 10 to be uber secure?
if my memory is correct this is because they don't have access to $password; they get md5($password) from the client and to store that in the database with a salt need to run md5() again.
oh ok I thought the usual MO was:
if (md5(password + salt) == stored value) ..
By the way, if anyone is wondering how VBulletin forums store passwords... It's md5(md5(password)+salt).