Actually napalm death has an even shorter song than that. They released a dual single release with the Electro Hippies that was included as a bonus disc on the comp Grind Crusher that clocked in at a whopping 1 (yes ONE) second in length, which holds the record for the shortest song ever recorded and the shortest single ever released. It's all in their VH1 bio.
http://www.vh1.com/artists/az/napalm_death/bio.jhtml
So there you have it, I do believe I win this thread.
Other really short songs are Jar by The Suicide Machines (0:03) and F*ck the Kids I and II by NOFX (0:07), Marco-Polo by Guttermouth, Solar Pannel Asses by The Locust (0:26) Coffee Mug by The Decendants (0:33)and NOFX, the Locust, Black Flag, Circle Jerks, Minor Threat, and many many other punk/hardcore/grind metal bands have several other songs besides the ones listed under 35 seconds in length. Pink Floyd also has a bunch of really short songs on Tree Full of Secrets.