I’ll keep this post short and straight!
If you are one of those who are still not allowed to use Google+ Project, then you can use following method to get/send an invite:
If ‘A‘ is a guy already using Google+ and ‘B‘ who wants to use Google+, then:
- Ask A to add B as a Gtalk contact.
- Ask A to create a new circle and add B as a contact in that circle.
- Then, A should update a status message in his stream marked to the newly created circle with B as a contact in it (as you do on Facebook using lock icon for lists).
- After the message has been posted, the B will receive an email which acts as an invitation email.
- That’s it! Enjoy!
This method worked for me. Let me know if it works for you as well or not.