Jesse McCartney writing songs for JB's next album

We had a chance to catch up with Jesse McCartney yesterday and he spilled some MAJOR Justin Bieber news -- he's working with J-Biebs on his new CD! Jesse tells M:

"Justin's a really nice guy. I'm actually writing a few songs for his next CD."

When we asked Jesse if he had any advice for J-Biebs (afterall, Jesse knows all about being an idol to millions of teen girls from his Dream Street and