"No Myth," the superb first single from March remains as Penn's only top 40 hit; it hit #13 on the charts. The incredibly catchy song received a bunch of airplay back in the day and the video was in heavy rotation on your favorite video music channel, as well. Penn was actively involved in the production of the video, mostly because he didn't want it to look too commercial, and I think that he succeeded for the most part.
Penn remains active in the music industry as of this writing, with his wife, Aimee Mann (formerly of 'Til Tuesday).
Cool trivia fact: Penn may have been cursed by the infamous "best new artist" problem -- he won the 1990 MTV VMA for Best New Artist. (Ironically, his wife also has the same award -- "Til Tuesday won the 1985 Award). See the comments section for a list of the VMAs for Best New Artist (current as of this post).