Do both parties have to sign when filing joint tax returns electronically?

Both people have to sign the return electronically. As per IRS document:

http://www.irs.gov/uac/FAQ's-for-Preparing-and-e-Filing-Your-Own-Tax-Return

Both people have to get a PIN and sign, except if the spouse is unable to signbecause currently serving in a combat zone (full details are in the providedIRS FAQ).