Gustavo Dudamel picked up his violin Tuesday for a chamber-music concert with members of the Los Angeles Philharmonic, and Mark Swed's LA Times review is here, with blogosphere commentary from Roger Bourland helping to fill out the picture.
Among the titan conductors who also perform on an instrument these days, the names I can think of are Daniel Barenboim (piano), James Levine (piano), Lorin Maazel (violin), and now Dudamel. I must be missing someone, though I can't think of whom. Myung-Whun Chung doesn't play piano anymore, I'm pretty certain, and Gerard Schwarz doesn't even list his career as co-principal trumpet in the New York Philharmonic trumpeter in his official bio. Others?
Update: Readers have written in to say that Antonio Pappano performs on piano (love alliteration), that Alan Gilbert also plays violin (must be an under-45 thing), and that Osmo Vänskä occasionally pulls out the clarinet. I mean to open the comments earlier, and they're open now.