I just installed the PUSHMAIL app which enables push mail notifications with providers like Gmail. however, I wasn't too happy with the stock sound that the PUSHMAIL app gives off because it's kind of quiet. so I went in to my iPhone's directory via SSH and I went to the following directory: user/application > then just look for the date that you added the PUSHMAIL app -you'll then double click on the app itself within your SSH program and you'll see the notification sound that's name "P.CAF" -I used my favorite email sound and renamed it "P.CAF" and SSHed it back in the same directory. -I restarted my phone and the change went in to effect. now I hear my "you've got mail" sound every time my PUSHMAIL app does it's job. this is great because now I have my check mail option on manual which means my battery life should be better.