Yes, Rahul Saxena has sung his first song in bollywood.
The film is Jawani Diwani, music by Sajid Wajid.
It was only natural that Sajid Wajid selected Rahul Saxena, as he sang 2 songs from their movies in the gala rounds of II 1.
anyways....here's the link:
http://bollyfm.net/temp/mp3/m-j/jawani.php
The song is Tere Ishq mein. There are 2 other singers, but for Rahul fans, it will be easy to detect his voice :)
have fun.