There has never been an official Pearl Jam acoustic release. Every Pearl Jam fan has a bootleg of their awesome MTV Unplugged performance from 12 years ago, but for whatever reason it was never released as an album. Eddie and the boys unplugged produced a simply awesome sound.
Pearl Jam is releasing their first ever full-length, mostly acoustic live show on a double disc CD entitled "Live at Benaroya Hall October 22, 2003". It's due July 27th and it should be awesome.