"Facebook wants more friends. And it is willing to pay for them."

http://www.nytimes.com/2011/09/27/us/politics/in-turn-to-politics-facebook-starts-a-pac.html?_r=1&ref=politics

Facebook, the social networking site, is more politically involved that its average user base.

The company, which began its lobbying in 2007, represents the PAC as a method of letting their employees views be heard in Washington.  But the thing is, the privacy issues surrounding social networking sites leave gray areas yet to be cleared up by legislation.  The company's presence in D.C. could lead to even more abuse of users' information.

Google has a PAC too, it's not as new, it started in 2006, but it has already spent over $345,000 on congressional campaigns.  The involvement of Google also calls into question the regulation of monopolies. 
"Last week, Eric Schmidt, the chairman of Google’s board and the former chief executive, testified before a subcommittee of the Senate Judiciary Committee on the issue of competition.
Mr. Schmidt told the committee that Google is in “the area” of a monopoly, but is engaged in fierce competition with other companies. " Seems to be a contradictory statement.

Corporations shouldn't have any influence on politics.  They are not human beings and therefore cannot be citizens and therefore cannot have freedom of speech, or any of the other rights held by American citizens.