ALERT: After their show at MSG with R.E.M. and The National, Modest Mouse will head to Brooklyn for a just-announced late show at the Music Hall of Williamsburg. Tickets for "A Morning with Modest Mouse" are on sale now (but probably not for long)! If you miss out, there's a free (okay, $3 suggested donation) Medeski, Martin & Wood (pictured) performance in Prospect Park at 7p.m. -- you'll get to bed much earlier. EVENT: CNN's......