iTunes 10.6.3 just showed up on Apple Support Downloads.
At the end of March version 10.6.1 was made available.
What happened to version 10.6.2?!

Sorry about sticking this in the wrong forum to begin with; don't know what possessed me (other than inattentiveness). Thanks for moving it, dianne.

Doesn't answer grelber's question, but is pertinent.

In the past, Apple (and other companies) have been known to skip versions if a version is nearly finalized and shipped to developers and beta testers, and then a showstopper bug is discovered that requires significant effort to fix.