Yesterday I did very non scientific test with N900 in real life usage, being connected the whole day: http://bit.ly/N900Connected

In the end I was really impressed about how the device allowed me to be online and connected the whole day - though in the end battery was almost dead and with little larger usage a'la teenagers IMing all the time battery would have died much sooner.

Any best practices and tips on how to improve battery performance and still be connected online the whole day? I already switched off 3g when not needing it and switched off vibrations.

However I was thinking whether there is an application that would selectively shutdown the network connection if there hasn't been any updates, then wait and reconnect - reconnecting also back to Skype and Facebook's Jabber .. and polling messages that might be there waiting for delivery. Or would that kind of trickery actually use more resources?

I liked the article, very interested to hear about some real world scenarios about how the battery holds up. This isn't quite the application you were after, as this purely handles closing idle connections, but it's getting positive reports about battery life. I can't test this personally yet, as I do not have an N900, although I am hoping to get one in April and join the fun

http://talk.maemo.org/showthread.php?t=45053 AutoDisconnect, this will probably be one of the first downloads for me.

This is very nice.
Another fellow also made a test with heavy use, it lasted for 5 hours under that test. Here is the thread.

Mine also lasts for a day or so with moderate usage, and about 5-6 hours of constant use.