Thanks DJ Prem for the heads up on this.
The Microsoft Beta Team have opened a new service for testing in the United States, which allows an MSN user to send a text message (SMS) to anyone on a supported carrier. Verizon are the first to implement the MSN Mobile features required fully, other countries and carriers will follow shortly.
Mobile messaging enables you to send text messages from MSN Messenger to the mobile phones of your friends and family, even if they are not on your MSN Messenger buddy list!
Testers were asked to check BetaPlace often to see if their carrier has been added, indicating that Microsoft is confident the new MSN Mobile features will take off.
When MSN Messenger 7.0 is released its likely that this service will be a subscription option.