The other day, Sparrow was unleashed on to the iPhone. I said in the post that it was one of the best email clients for the iPhone. It was great for multiple account users who need to keep on top of their emails. It's also absolutely gorgeous and a joy to use.
The only problem, and a problem which is definitely a deal breaker, was the fact that it doesn't have a notification system of any kind. The reason for this was that Apple stopped the devs implementing a push notification system into the app, days before it was going to be released. It was due to some technical issues and what not, which we won't go into.
Well if you're jailbroken you can now get push notifications via a Cydia tweak. It's called Sparrow Push and is free on the Cydia store. Just search for it and you should find it. You might not find it right away, give it some time and try again later, the servers may not have updated for you yet.