I am using it on my phone, and it seems to help, I haven't tried it on the tab yet. It would turn off your wifi while the screen is turned off, only turning it on for a brief period occasionally to allow things to sync. There would be some power savings, while allowing the tab to still keep you alerted periodically.
However, what Pablo suggests sounds good, and would probably save even more juice if you don't need to be alerted while the tab screen is turned off. I think I will check out those apps.