No real point using OpenGL ES, as JSR 184 (the M3G format) will be put on top of it when available, and you’ll need more Java method calls, therefore probably slower than an app using the M3G mechanism.
Another useful one is Mascot Capsule, who have now got a Blender exporter in beta on their website. This engine is much faster than M3G on the devices which support it (primarily in Europe this is the recent Sony Ericsson handsets) mainly due to it’s use of integer mathematics, whereas M3G uses a lot of floating point, which mobile phone processors aren’t exactly good at.
I am aware of a very very very high profile game in development using JSR 184 (and Mascot Capsule) and Blender (although the team in question had to rewrite the exporter somewhat) but due to the wonders of the world I can’t mention it yet.
M3G is a very nicely designed standard, but the handsets able to really use it are still not getting into the market quite enough. There are also bugs in the different handsets. Sharps used to have a problem with Sprite3D projection, for example. The newer Sonys (k700 onwards) and the new Nokias (6630 onwards) are really getting good though.