Used in prominent social games such as Mafia Wars, Jambool’s Social Gold payment product allows app developers to build payment systems into their games and apps, similar to Facebook Credits except Jambool’s solution is a mite cheaper. However, Facebook Credits has stung Jambool and its peers enough that cofounder and Amazon veteran Vikas Gupta railed against them in an interview last month with Inside Social Games.

Though neither Google nor Jambool are commenting, TechCrunch places the purchase price between $70 million and $75 million. It would certainly be a feather in the cap of Google’s much-rumored about social gaming network that it’s setting up with Zynga.

It seems to be a classic case of acqui-hiring as Slide’s 100 social media developers and founder Max Levchin, also famous for cofounding Paypal, will jump aboard the good ship Google. TechCrunch and The Wall Street Journal put the price tag at $180 million.

“As the Slide team joins Google, we’ll be investing even more to make Google services socially aware and expand these capabilities for our users across the web,” said Engineering Director David Glazer on the Google Blog

TechCrunch reported last week that Vice President of Engineering Vic Gundrota will be leading the company’s social networking efforts (“social czar,” as GigaOm dubbed him). Gundrota has been focused on Android and Google’s mobile efforts, but has had a hand in numerous Google endeavors. GigaOm applauded the selection, noting that “mobile looks to be be Google’s best front on which to wage a social war.”

So how is Facebook responding to the mysterious Google Me social network in development as well as recent news of a Google social gaming network and a music service? VentureBeat says CEO Mark Zuckerberg has turned on the neon “Lockdown” sign in his office — sources tell the publisher that for the next 60 days the Facebook office is open on weekends as engineers hunker down to upgrade the Photos, Groups and Events sections ahead of a Google launch.

But they’re still not on top – Slide holds that coveted spot. (Slide rang in the New Year with a $50 million infusion). And this new round come amid whisperings online and offline that RockYou is in the throes of the big decision all burgeoning onliners must face: bail out now with a respectable, but relatively minor valuation, or push ahead and hope it can beat out Slide and other up-and-comers (like Meebo and Ning) in the social networking ad game?

While widgets have been installed on zillions of users’ pages, monetizing the space with ads has proved to be an almost Sisyphean task. Also, Facebook is about to unveil a significant redesign, making it harder for applications and widgets to go viral – which could be good or bad news for more established brands (it will definitely stymie the small fries).

Slide’s apps can be found on the major social sites like Facebook and MySpace, and their advertisers include Fortune 50 companies as well as top entertainment and CPG brands. The company aims to marry interactive advertising and fun – and it seems to be working. More than 170 million users interact with their products, from SuperPoke! to Fun Wall.

Some industry observers aren’t as enthused with Slide as others, calling the move to New York a desperate attempt to inject confidence into the unproven field of advertising in the social networking space. And according to Forrester Research, marketers spent about $600 million on social media (a fraction of the $18 billion spent on online advertising overall).

Slide was launched in 2005 by PayPal co-founder Max Levchin.