Verizon is expanding their 700 MHz - 4G network rapidly this year.
The latest rumblings on the web say that the outage was related to an overloaded server which keeps track of users preferences and settings. It's pretty likely to be related to recent expansions in the network and the number of users. Verizon's LTE network is a growing organism - early adopters, like us, will have to take the good with the bad. Actually, even those who think they have opted out of new technology are affected - there is no hiding place really as the internals of the network are clearly going to share a lot of stuff. The only parameter really is how much we are paying for our adventure.