I was able to replicate what you described.

My home machine hadn’t updated yet so I tried “software updates” nothing…

I recalled seeing the title of this post come over your twitter stream so I decided to see what you had written. Turns out you hit the nail on the head.

I opened the .Mac preference pane and within a few seconds I was prompted to download the MobileMe update.

I can talk myself into how this makes some sense for Apple. However, I have a hard time making sense of it from a paying service subscriber point-of-view.

Thanks!