If you haven't received your Google+ invite yet, then here is the best thing we can offer, the Google+ Theme for Chrome.
OK. Well it’s not as good as an invite, but it is the best we have found so far. The theme itself is actually not great! The Google+ theme for Chrome is an unofficial version and this is why it looks like it hasnt been finished completely.
Anyways, if you want to check out the theme for yourself, then you can head over to their the download page here.