I commute by bicycle, and my brain doesn't absorb things well through spoken word (so audio books aren't very useful to me). So I don't learn much new during my commute.

However, that commute time is of immense value to me. Much like shower time, I often find myself reviewing various technical problems and coming up with "aha" insights about them. Perhaps not the sort of learning that you're talking about, but I think it counts as learning nonetheless.