Does anyone know if one can have two blackberries (one on Verizon and one on T-Mobile) for one email account via BES (ie, two separate BES licenses -one for each device). Is this even possible?? Thanks....

Yes, you can use two BlackBerrys with one email account. just not at the same time. When you activate the second BlackBerry, the first BlackBerrys information stored on the BES server will be over written.