I am not aware of an "edit" to display information about the actual network in use, but on GSM BlackBerrys you can find out the MNC of the network you are currently on.
Choose Options / Advanced Options / Host Routing Table. Scrool down the list of entries to see which one is highlighted. The highlighted one is the active one. If you look at the first 5 characters of the name of the active entry, that is the MNC code of the current network. Below is a list of the most common MNC codes:
31041, 31017, 31015 = Cingular
31026 = T-Mobile
31038 = Cingular Blue (former ATTWS)
If you need to look up other MNC codes, there are long lists of MNC codes on the web (try
www.howardforums.com).