Yep i was wondering too about that issue: as a full mated couple they won't have sex just in the 3 nights of the full moon, so:

1/ sex with a wolf (can be amazing with the knot and all...) very kinky and naughty too.
2/ will Sam be able to change at will?
3/ Dean will be changed too and follow his mate's shifts.
4/ which one will top? will they switch roles ?