Update: The BOGO offer is only allowing a free Droid Eris and not a buy one Droid and get one Droid – you can only buy a Droid and get an Eris free.
Naturally they expect you to enter into a 2 year service agreement for each line. And data costs add $30 per smartphone to any family plan.
Still, this is not a bad overall deal. Presently the Verizon stores sell the Droid for $299 less a $100 rebate and the Eris is $199 less a $100 rebate.