The person with whom we spoke said that it didn't actually cover any amenities, like Internet service, but was just an additional $20/night fee.
Updated info from same source (
www.lasvegasadvisor.com):
"June 11, 2010 ... today we can confirm that the amenities covered by the fee include Internet access (including WiFi), local/long distant/domestic calls, access to the fitness center, and boarding pass printing."
Big whoopie.