Yes, you can either import your Google account contacts or copy and paste emails in bulk. You'll see the option when you visit People and click Invite People. Follow these instructions to invite people individually, or in bulk.
For copy and pasting bulk emails when inviting multiple email, the formats we accept are:
Comma separated: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org
Paragraph break separated:
Name/email format from email fields: John Doe <email@example.com>, Jane Doe <firstname.lastname@example.org>, Bob Dole <email@example.com>