Exactly, iPod events are always just about iPods. Never has a Mac, portable or otherwise, been announced at a special iPod event. Macs are announced at trade shows or their own events. iPod design refreshing is done once per year, but something less significant such as a memory/HD bump can happen again at a later time.

People forget that there are always two notebook refreshes per year. Excluding announcements at Macworld in January, these are usually in the spring and fall. Take a look at the history of announcements over the past 8 years if you don't believe me. The biggest announcements have tended to be done in January at the Macworld keynote.