"Linkedin IPO: net revenue $100M, market cap $4B. Google IPO: net revenue $800M, market cap $24B." http://twitter.com/akkartik/status/72519743835348992
Seems pretty reasonable.
Seems pretty reasonable.
(There's profit to consider too, of course, but the business models of these two companies are similar enough that one would expect them to have similar margins.)
Google (gross revenue) was at 3x. http://www.sec.gov/Archives/edgar/data/1288776/0001193125041...
All this is details. It's pretty clear that prices aren't crazily inflated.