All these folks are missing the bigger picture: the launch of a stereotypical web2.0 website by a couple 20 year olds is only the BEGINNING.

Chances are if some kid launched a web2.0 mashup at 20, at 25 he would be bored and paying with more mature ideas(which some could argue isn't inherently a better thing).

does one have to do meaningful work only when you are a wise old man/woman?

been done:

http://www.readwriteweb.com/archives/crowdsourcing_million_heads.php

Looked quickly at your link - could be mistaken but it seemed to be the public submitting ideas to one company to implement. The idea on my blog, is match-making the many teams to solutions or untapped idea opportunities from the public.

And burn them when you get there!