Don't have any mac experience, but updates on the iPods have been rare. The new nanos I bought my kids for Christmas have on had one update in four months. This is much different than the weekly updates I get every Tuesday for Vista. It just seems to me that Apple does their homework a little better than the guys from Redmond.
Historically, the first updates to Mac OS X after a major release (i.e. 10.4.0) come within a few weeks of the official launch. After Apple declares the OS Gold Master, it takes a few weeks to roll out to retail....in this time, they continue bug-squashing development for that 10.x.1 update.
Since iPhone is running some version of Mac OS X, I'm guessing iPhone will be the same way, although updates may be more user feedback-based since there are no discs to press between gold and launch.