Is Google doing some 11th-hour negotiations to try and snatch a Facebook deal out of the hands of Microsoft? Valleywag placed Google co-founder Sergey Brin at a hotel with members of Facebook investors, Greylock – the timing was a bit odd as Google had just wrapped up its 3rd quarter earnings call. Also there was a Google exec said to be part of the negotiating team between Google and Facebook. What – if anything – is going on?

Valleywag speculates that Google is attempting to woo Facebook by lining up private investments for the company rather than making an investment itself. In return, Google would simply want an advertising deal with the social network. It’s an interesting theory, made more interesting when you realize that Facebook’s current ad deal is with Microsoft – the same Microsoft thought to be the front-runner towards buying a stake in the company.

Valleywag had an interesting rumor on that front a couple days ago when they suggested Facebook and Microsoft may sign a deal that would give Microsoft a share of the company, but would allow Facebook to terminate their current ad deal. This seems somewhat plausible as Mark Zuckerberg’s comments at the Web 2.0 Conference suggested Facebook was hard at work on a new kind ad platform for the site.

That angle very much reminds me of the recent Microsoft/Bungie split where Bungie is said to have asked Microsoft for their freedom in exchange Halo 3 and a long-term share in the company (or else they could have all just quit) – Microsoft obliged and maybe they’ll do the same here, letting Facebook out of its advertising contract in exchange for a piece of the company.

Even more interesting would be if Facebook does the deal with Microsoft, regains control of their ads, and then turns around and signs an ad deal with Google – while Microsoft would be a minority owner in the company. Something tells me Microsoft would have provisions in their agreement to not allow that to happen…

It should also be noted that Google now appears to be very much active in developing Facebook apps, as the official Google News app was just released. Google has been notably absent from this party for a while, could this be a sign of an impending relationship between the two companies?

If Sergey Brin and Google are able to pull off their own deal to get a piece of Facebook, I think the Internet might explode. I know Steve Ballmer would.

[UPDATE 10/20]: Valleywag is now reporting that there is some important Facebook company-wide meeting going down on Tuesday. Could this be the funding announcement to employees? We’ll see.