According to this blogpost
Web 2.0 is about finding new ways to interact on the internet and collaboration, at least to a certain extent. Those of us in the know realise what Web2.0 is really all about - putting things on super shiney tables and painting them with gradients and candy colours and shiny silver and stuff.
Organised into 3 distinct colour groups - neutrals, muted tones and bold colours, you may recognize a few of the shades from some of your favourite Web2.0 sites. Now you can quickly and easily assemble your own colour scheme - simply choose any number of bold or muted colours, then add as many neutrals as you see fit - you'll have a Web2.0 masterpiece in no time at all!
These are just the programs I have heard of. Surprising how many others there are.