No, not full strength. But at about 1:3 with water, it considerably increases the surface tension of the paint.
I reckon it\'s most useful for getting paint to stay exactly where you put it, though. It reduces capillary action and causes the paint to gather. Fine lines of paint remain fine, and don\'t spread. Also used for washes, because of the gathering qualities.
As Einion noted, it remains water soluble after drying, and the surface can get a bit tacky if you paint over it again. Just let it dry thoroughly each time you go over it.