What you see above is the same menu found in Google Maps 4.60, but on the left is how it appears in Android 2.3 (Gingerbread) and on the right is how we see it in Android 2.2 (Froyo). There is no secret option to turn this design on, it was found by a Freenode IRC user canadiancow who noticed that API level 9 (Gingerbread) was a folder within the APK and recompiled it as an API level 9 app and it came out like this.
I for one think the new UI design is very, very nice and makes Android look for more profession and slick. It looks very Adobe Air/TweetDeck which is a good look. What are your thoughts?