Pinterest has dropped its invite-only policy, announcing open registration for prospective pinners. Now, besides being able to sign up with a Facebook or Twitter account, users can also sign up with just an email address.

Based on the social network’s huge growth, you wouldn’t think that it was an invite-only site. Pinterest grew 4,377 percent from May 2011 to May 2012, becoming the fastest growing social network early this year, according to a ComScore report.

Now that the company has developed the capacity to handle open registration, it’ll probably continue to see its numbers grow. Add that to potential international users—the site received $100 million recently to fund its international expansion.

Do you think Pinterest will see Facebook-like popularity abroad?