While searching in Google Codes, I found a project which is very close to JVNMobileGIS - Mobile Trail Explorer. Very interesting! They have what JVNMobileGIS doesn't have: GPS tracking.
I applied for project membership immediately. Thanks Tommy for your fast response and approval. I will try my best to contribute to the project and improve my project as well.
Now I can be a truly developer :) (I hate to be a Team Leader).