MAC Brush Cleaner is excellent for quick cleaning brushes, without having to wait for them to dry overnight.
I dribble some onto a cotton pad, then wipe my brush hairs from ferrule to tips, rubbing the fibers to get out as much as possible of the makeup. It has returned pink fibers to their white state quickly when i'm using the same brush to do both blush and highlights (my MAC 188 small duo fibre stippling brush).
MAC Brush Cleaner is no substitute for a proper wash. We really need to wash those brushes regularly. But it's great when you're in the midst of creating a face and just gotta quick clean a brush for re-use or on brief trips and you don't have time to do a thorough brush washing.