Not sure how to specifically answer that question in reference to charging only, however, when you plug your iPod Touch into a USB-port it will chirp when syncing with iTunes is complete (and when it begins?). Just turn it off as mentioned in the post's above if you don't like it.My 8GB ipod touch with 2.0 alerts with new email but also chirps every few minutes while charging from the wall charger. How come the charging chirps?
As noted above, I love the feature with MobileMe. Chirp, chirp, email.