"Previously, Synchronicity would display as a red, tethering-style bar over the iPhones status bar. This notified that a sync with iTunes was occurring, and removed that annoying Sync in Progress lock screen we all normally have to stare at while our iPhone syncs. In Synchronicity 2.0, that red tethering bar is replaced by a minimal, Greek Sigma icon in the status bar to indicate that an iTunes sync is occurring."
Ha, it's not a standard status icon found on the iPhone. Means that your phone is jailbroken and using the Synchronicity app. It allows you to use your iphone while it's synching instead of seeing the lock 'synching in progress' status. That's all.
Oh, wow, I've never heard if this app. I'm gonna check it out now. I hate when I'm syncing a lot of stuff over to my iPhone and I get texts that I really need to respond to, making me stop the sync to respond and start the sync all over again! This should all be remedied with iOS 5 soon, but that's still some 3 or so months away. No bueno...