Amtrak is testing e-tickets on the Downeaster (Maine to Boston service). Those are the only etickets that exist, and the test just began.

Separate from that, credits will now be electronic, and there will be no need to hold onto a paper credit voucher. Unfortunately only ticket agents in stations will be able to issue tickets against electronic credits. Pretty ridiculous - the credit is electronic, but you still need to wait in line to get a ticket and you can't use the machine!