Here in Europe we woke up to find Google had shut down the invitation process to Google +. So after a bit of testing I’ve found out the following how to bring your friends in to it while Google has a lock-down on the service.
If you have an invite to join Google+, right click on the invite link you were sent on email and save the URL. Paste that URL to Twitter or Facebook or email it to some friends. With any luck some of them will get in via that link.
I tried this by Tweeting my own invite link, and magically a few people managed to get an invite of their own. Most did not however, so this is not a full proof work-around. It seems to work if people waited a couple of minutes or refreshed the page after a minute.
The better, more guaranteed hack is one or both of the following.
An existing user on Google+ creates a new Circle, called (for example) Invites. They then add the emails of the people they want to invite to that circle.
An additional work-around – which also appears to work on its own – is simply creating a status update (it’s called a ‘Share’ on Google+), e.g. “inviting people” and then pasting the Gmail addresses of friends you want to invite into the “add people” box (Next to +1 and Comment links).
They should then get a copy of your status update in their email and link saying “Learn more about Google+”. They can then click on that and will get taken to your post, with a Join Google+ button.
Let us know how you get on in the comments below (ironically, Facebook powered).
Update: It would appear the last suggestion here is the simplest and most fool-proof.