Google+ Icon. Feel free to re-size for use as a social media button on your blog/website. Feel free to alter, as long as you don't violate Google's copyright. It's 500px square with a transparent BG, so you can also use it as a Dock Icon. There are NO restrictions on this that "I" am placing on it... It'd still be nice if you +fav'd or thanked me if you use it though.. Jussayin'...
Click to download the *.PSD file, or Right Click the image to save the *.PNG.
I do not know. Do I need it? Cause, yesterday when I visited my Google+ page there was written to simply login with existing Google mail. So, is it necessary to have an invitation?
To use Google+ there may be.. I had a pre-existing Google account too, but when I actually tried to join the thing on my own - it said it'd reached the maximum amount of people for now. Then I had to go looking for an invite. It's still in the Beta.
Yes, you are right! But i just entered google with my mail and registered for google+ freely. Right now I'm customizing my account and than I'll send you a link, bro!
If you include it in the "links" widget, on the right-side of your "About" tab, then it appears. Otherwise, anywhere you have your email, it's hidden unless you choose to let "everyone" (public vs. private) view it.