FB and Bing are together now.

Hmmm - at this moment, I don't think so...

Everyone knows you "google" something - I've never heard anyone say "FB" it, or "Bing" it...

However with Windows phones beginning to take more share of the market, people may become more familiar with BING in the future.

Although as I understand it, FB is losing users too - so could balance out.

For now though, Google, Bing and Yahoo are the main engines.

All the best, Mark