Fall 2007, Williamson can be seen and heard in the recently released Julie Taymor film Across The Universe, a movie musical featuring over two dozen Beatles songs. The film opens September 21, 2007, at selected theaters nationwide. Look for Williamson on screen as a member of the Circus Band!

During Fall 2005 Williamson toured with jazz pianist Fred Hersch, performing Leaves of Grass, a musical setting of portions of Walt Whitman's classic poem, sung by Grammy winner Kurt Elling. The recording on Palmetto Records has received critical acclaim.

Bennington magazine, September 2003: Williamson recently performed at the Jazz Bakery in Los Angeles with trumpeter and film score composer Mark Isham, and at the Spoleto Festival in Charleston, SC, with the Fred Hersch Ensemble, featuring vocalist Kurt Elling. He also recorded and performed at CAMI Hall in NYC with Manhattan New Music Project. In October 2002, he recorded selections from Walt Whitman’s Leaves of Grass, with music composed by Fred Hersch. In April 2003, In April Hubbard Hall in Cambridge, NY hosted An Evening of Jazz with Williamson on sax and woodwinds. In May he spent a week at the White Oak Plantation in Florida workshopping a new musical composed by former faculty member Ricky Ian Gordon, and sponsored by the Sundance Institute. He also produced and performed on two CDs this past spring—one for New York guitarist Tom Chang and another for Vermont vocalist Evita Cobo.