At first, VoLTE will be used to deliver "Rich Communications Services" (which look like something similar to what Voice over IP/Video over IP outfits offer today) rather than completely replacing narrowband voice. It will be awhile before Verizon is willing to commit to that, due in part to LTE outages in late 2011.
On the flip side is MetroPC, which has pushed VoLTE as hard as it could.
Then there's Sprint, which will stick to voice over 1x for the foreseeable future, but routes Direct Connect over IP. Sprint's latest DC incarnation seems quite similar to one facet of RCS over LTE.
Resurrecting an old thread, I saw B41 LTE in Magnolia, MS on I-55 the other day. Ran a speed test and it was in the mid 30's. I was traveling south to north on the interstate and saw what appeared to be the alpha and gamma sectors. This is new to me!!