Or even on the other end if a license owner gets an email saying that the add-on has an update.

exactly

Yea this would be a good idea. Although, I'm not thrilled about the marketplace connection idea; if we must use it this would be a great addition.

I'd like it if when you upload a new version of your add-on, there was a text box on that page, and anything you type there posts to a Versions page underneath your block detail page. That versions page would have a "monitor" button, so that anybody could subscribe or unsubscribed to be notified of version updates, and anyone who bought that block would be automatically subscribed.

the version note, and sending out an email alert with every version note, should be optional though, cause often it's just a little change you're making, which isn't really a critical update for people. don't want to annoy them into unsubscribing.

What would be nice is if add on and Concete5 updates would just automatically update, just like all the programs on my computer do.

Now THAT would be nice !!!

wait, no they dont.

You have to hit yes you want to apply updates. Yes you don't have to do much more than that to update your windows or mac box, but a human still does approve applying updates.

With websites & a CMS I think this is even more important. This stuff is all open source and people can customize/tweak things in any number of ways.. If we were to just automagically do things behind the scenes we'd run as much chance of breaking things as we would helping things.