Of course the widget shows your achievements but it also shows how you rank overall and just in certain games, 1) overall to all facebook members with the widget and 2) those in your network(s). So if you and your friends are all playing say last stand a zombie defence game you could see your ranking in comparison to those in your uni and overall on facebook with a numerical ranking.
It's time, imo, CB got in on the act, there was a poll recently about if CB should have a facebook widget and I think the main reason it wasn't a resounding yes! was that not many knew what facebook was at the time or they didnt think of the possiblities. (If you still dont know what facebook is, think myspace++ and as myspace dies facebook has everything it needs for immortality).
The CB Widget :
Picture of your main character's Image with name.
A few categories, score, MPR etc that are all ranked on everyone on facebook and those in network.
Same as above but a few stats that can be selected, like STR rank or FB rank.
Top 3 highest NW items on the character named and ranked.
Many of it would be active links to CB when clicked on and the referal link so that the players displaying their CB widget would be geting their friends joining and geting paid CB$ for it.
If done right I think this widget would end up being the largest pull of new players CB has seen (including slashdot) and the people coming to try CB wouldnt be unwelcomes (as you often get off the poll online games sites filled with l33t kids and the like) but people just like those already playing CB.
In short there will be a few big names that everyone knows on t'interwebs, google, youtube and facebook, CB should embrace facebook as unlike myspace it isnt going to be a passing fad, and sooner rather than later imo.