Many wireless networks (hotels, corporations, Boingo, etc.) require you to log in on a web page in order to access their network.  Network Manager should support this by letting me specify a script to run when logging into a particular access point, before marking the connection as active.

This becomes a real nuisance when NM automatically connects to one of these access points, sends out a signal that the connection is active (before I am able to login), and programs like Pidgin begin trying to connect before I am authorized to use the network.

Eventually, companies like Boingo, T-Mobile, BT, etc. could possibly release their own login scripts for customers to use with this mechanism.