Via a software update last night, the UI has changed a little. There is now a place to dynamically select (and add) your 911 address. Given the mobile nature of MagicJack service, this is a very good thing to have, and provides for the best safety as well.
I got the update as well. Very impressed that the 911 service is a priority for such a young service. MJ has a bright future. Makes me glad I didn't prepay $200 for a year of service with another voip company.