Yesterday, Fandango and Groupon were both updated to support Mango instant resuming.
The Groupon app is considerably smoother after the update and feels more polished as a result. You can find Groupon in the Marketplace for free.
Fandango, despite the new update, is still not perfectly smooth. Also, despite the addition of instant resuming, when returning to the app, it still has to reload the current list of movies or showtimes you are on for some reason, which completely kills the experience of instant resuming. It is somewhat faster to return to Fandango, however the app still needs more work to be perfect. You can find Fandango in the Marketplace for free also.
Doodle Jump was also updated, however the changes in the update are currently unknown since Doodle Jump was updated to Mango a month ago along with numerous other Xbox Live titles.