All Blogger blogs will have it: http://googleblog.blogspot.com/canvas.html

Here's a working example: http://epeus.blogspot.com/

The content of the first link:

"Google Friend Connect
We're sorry.

We were unable to process your request. Please try again."

Bill Mac:
Yes, that's right. I placed the link to show that the page is available at *.blogspot.com and has something to do with Friend Connect. Some blogs already have the feature, for example this one: http://epeus.blogspot.com/canvas.html?url=http%3A%2F%2Fwww.google.com%2Ffriendconnect%2Fgadgets%2Fshare.xml&canvas=1&site=08327824258157094031&bgcolor=%23FFFFFF&caller=http%3A%2F%2Fepeus.blogspot.com%2F&view-params={%22skin%22%3A%22{%22HEIGHT%22%3A325}%22%2C%22startMaximized%22%3A%22true%22%2C%22disableMinMax%22%3A%22true%22%2C%22features%22%3A%22comment%22}

Ah, yes, now I see. (Kinda figured that was the point.)

Maybe that's related to this new section in the profile page which I spotted a couple of days ago on a Googler's profile who works on the Blogger team:

http://blogoscoped.com/files/more/blogger-follows-these-blogs.png

http://www.blogger.com/profile/14908970658480399870

Is this like socialstream?

It's peoplesense = friend connect http://www.google.com/friendconnect/ .

Since I've "friendly subscribed" to that blog (pointed by Ionut), I've a new link in my google account :

Google Friend Connect : http://sites.google.com/c/ps/

the site doesn't work.

That gets added whenever you subscribe to any Google Friend Connect sites, like the ones here:
http://www.google.com/friendconnect/home/examples

OK thank you Tony
I've tried to rewrite the javacript on a test blog, but it alwaysshows
<<
A system error has occurred
Error 400
>>

:-/