Edmunds.com has a decent write-up on this:
http://www.edmunds.com/fuel-economy/the-ins-and-outs-of-electric-vehicle-tax-credits.html
Says this about the federal tax credit:
"If a vehicle is being leased, the credit stays with the leasing company, which is the actual owner of the car or truck. In most cases, however, the tax credit has been factored into the cost of the lease, so the customer still benefits. Lease programs for the Chevrolet Volt and Nissan Leaf, for instance, include the $7,500 as a credit toward the down payment."
I just applied for the $2500 California rebate since the instructions on the application clearly state that the lessee is eligible.