Invites are currently disabled due to the overwhelming response as people clamor for access. There is however a way to invite your contacts, even though the invite mechanism has been temporarily disabled for Google .
Quick steps for sending out invites under the radar:
1. Create a Circle called “Invites” (or whatever you like).
2. Add by email the list of friends you’d like to send an invite to or drag friends into that circle if G found a bunch of your contacts,
3. In your stream, create a post and share it with your invite group.
4. Share to that group.
Your list will receive an email with your stream update and a button called “Learn More About Google ”. By clicking that button, they should be able to sign up for the service*.
*The one exception to this is companies using Google Apps can’t create profiles, which means they can’t use Google . So far this would be my biggest complaint as my company uses Apps and all my contacts are done with my corp email. Instead, I’m forced to use a personal email that I don’t use for anything else.