Very nice! The Middle-Eastern-sounding Connect alert is a cool surprise; it'd be neat if you could create a matching Disconnect alert instead of just using the Contact Sign Off. You could do something as simple as just transposing the same figure down an octave or two if you don't want to rewrite it using contrary/opposite motion.

The Message Received/Sent alerts use some very pleasing melodies. I think you could probably speed up the tempo on both so they're more like ornaments.

I noticed that your actual sound files go on much longer (sometimes a good five seconds) after the reverb decay has faded out. If you don't want to shell out the money for a shareware AAC editor, you can use iTunes to shave off what you don't need.

Very nice.