I got my first invitation to join a LinkedIn group – as it happens a group looking at Web 2.0 in the HR space. LinkedIn seems to have gone into innovation overdrive lately, no doubt spurred by the stratospheric rise in social networking. The site really does look like its achieving critical mass and in my view is the most interesting social networking play currently. I remember a few years ago the total scepticism which greeted any suggestion that the site would make money. I guess the case is now being proved… Watch this space.