Facebook has become such a popular social networking site that some companies are betting their businesses on it.

Participants in a panel at the Web 2.0 Summit conference in San Francisco Thursday cited the impact of Facebook.

"We looked at the Facebook platform before it launched and came away with the conclusion that this could be the greatest paradigm shift in technology since the Internet itself," said panelist Ali Partovi, CEO of the iLike music discovery service.

iLike bet close to 100 percent of its business on Facebook, he said.

"We made a very big bet. We basically decided to halt work on our own Web site and spent the next [several] weeks that we had building a Facebook application," Partovi said. iLike's own Web site, meanwhile, is used to drive traffic to the Facebook application, he said.

"Literally, within the first 24 hours, our Facebook registrations exceeded the rest of our Web site," by a dramatic amount, he said. In the first 12 hours, iLike signed up 10,000 users, followed by 10,000 more in the next three hours and 10,000 more in the next two hours, he said.

Facebook application developer Slide is probably allocating 35 percent of its efforts to the site, said Slide Vice President Keith Rabois. Slide decided to invest in Facebook because it created an open environment that encouraged developers to make money for the first time.

"That has been a sea change," Rabois said.

Facebook opened the floodgates for a raft of innovations, said Seth Goldstein, CEO and co-founder of SocialMedia, which also has developed applications for Facebook. Facebook has 2 million users, half of whom use it daily, he said.

"There's a level of engagement," inside the Facebook platform, he said.

Another panelist noted Facebook widgets. "The neat thing about the Facebook platform is you can actually talk to friends through widgets, thorough the APIs," said Lance Tokuda, CEO of the RockYou photo-sharing site.