Extending Zawinski's law [1] to the web: Every website expands until it becomes a social network. Websites that cannot so expand are replaced by ones which can.

[1] http://en.wikipedia.org/wiki/Zawinski's_Law_of_Software_Envelopment

Google search is pretty big. Is it a social network?

Zawinski's law didn't really apply to windows either.

But it's a good question. Both edges of the feedback loop between search and social network are interesting:

a) Social networks where we have to manually link to friends will not last.

b) Google's integrating search with notebooks, groups, hosting, email and IM. Perhaps those are primitives for a social network rather than an OS.

c) Making search more relevant using a social network is perhaps still a valid approach, in spite of the lack of success so far.

The story of search is not finished.