Last night's six-act, five-and-a-half-hour show at the Living Room (one of numerous events this week commemorating the venue's tenth anniversary) would have felt rather drawn out for anyone unable to divert himself by hopping on the stage to join in on his favorite songs. Which perhaps explains why there were so many musicians in attendance — and why we only showed up for Joseph Arthur's headlining set. What started as a quiet, open-mike-type performance turned into a full-on jam session, with “special friends” like Scottish singer Angela McClusky and guitarist Jennifer Turner joining in, and R.E.M.'s Mike Mills collaborating on a show-closing cover of the Velvet Underground's “Pale Blue Eyes.” Arthur, meanwhile, had asked the non-semi-famous audience members to quit acting like cool New Yorkers and sing along. By set's end, in fact, we were ready for the party to go on all night long. —Elizabeth Black