As you may have noticed over the last couple of days, the Android Market hasn't been doing too well. Downloads have started, and then failed, failed to start, started to fail, and just generally failed in every imaginable way. There once was a time when clearing such-and-such cache would fix this sporadic issue, but it seems that even this black magic no longer suffices. Threads have been popping up all over the Android-tinted corners of the 'net with people unable to download anything from the Market.
This happens to coincide nicely with a Google Maps 4.6 update, which is said to bring some new and improved search features.