There are currently push notifications available for iPhones, Palm Pre and Blackberries each provided by their respective manufacturer. However I have heard nothing for Androids (probably because google does not actually sell the phones themselves. Are there any solutions out there at all?
Android doesn't have the same limitations that the operating systems of the devices from the various other manufacturers listed incur. So it's likely that the data or notifications already exist as an intent and you just need to register for a given intent in your application.
The methodology in your case would be the same as you would use on normal computer systems.
You could have your server broadcast or stream events to a background process you create on the android device.
In all of the looking I've done around, there aren't any services doing this today. The last-mile piece is a little tricky and it presents some interesting issues for both the handset manufacturers (imagine every app firing up their own phone-home daemon) and carriers (that's a lot of back-and-forth when you've got lots of clients keeping connections open).
I'm at a company called Urban Airship and we do push notification services for the iPhone and have gotten a lot of questions about doing this for the Android platform. I'd be curious to know if others would be interested in a service like this? Something that would have an (ideally) open source library coupled with the last-mile cloud infrastructure providing the notifications to the devices and apps themselves?
Was looking for same. Xtify is doing this now. developer.xtify.com. has a lot more than just push, but you can do just push if you want. I had a back and forth with one of their devs - he said soon you will be able to have iphone push (much less rich and no geo though) as well off of their platform, but for now, I just use for Android.
Why dont you go with the XMPP implementation. right now there are so many public servers available including gtalk, jabber, citadel etc. For Android there is one SDK is also available named as SMACK. This we cant say a push notification but using the XMPP you can keep a connection open between client and server which will allow a two way communication. Means Android client and server both can communicate to each other. At present this will fulfill the need of Push in android. I have implemented a sample code and it really works great.