Ars Technica has the news on Washington state's newest registration tool:

In 2008, the Pacific Northwest state became just the second in the union to offer online registration. This week, a new Facebook app created by Microsoft (a Washington company, naturally) will provide a new interface to let voters access the MyVote system.
Today, Washington and 12 other states, including Utah, California, counties in Nevada, Connecticut, Indiana, and others offer online voter registration.
"Facebook has millions of users, and a lot of users in Washington state—half of all Facebook members log on every day," said Shane Hamlin, the state’s co-director of elections, in a phone call with Ars on Tuesday afternoon.

It's no surprise that Facebook was consulted for this system -- the sheer reach of the platform holds clear benefits for Washington election officials. However, as with all online social networks, the need to accurately identify users who register will be paramount.

Online voter registration via Facebook may only be the first step. Perhaps soon we can expect full voting capabilities through our social media networks -- making the voting process even easier (at the potential cost of iron-clad security).