A good use of in-app updates - Basic to Pro upgrades

It's been frustrating to me that in order to get the advanced features of "pro" versions of apps that I already purchased that I would have to buy the app a second time at a higher price. Today an upgrade to TravelTracker with TripIt was posted that includes an option to upgrade to the pro version (with real time updates) for $5.99, only $1 more than the difference between the version I bought already and the upgrade. In the past I would have had to spend another $12 to get the pro version.

This, IMO, is a good use of in-app updates. I'd been pretty unenthusiastic about the whole idea until I saw this use of it. Bravo! Let's have more of that kind of use.