We recently reported that Google will be opening up their AdSense platform to third-party ad networks. Its a smart move for Google because it allows their publishers to run ads from third-party ad networks without the risk that they’ll leave AdSense. Its also good for ad networks who are looking for more distribution or to get rid of excess ad inventory.

But the elephant in the room is that Google is moving into an arena that Santa-Monica based Rubicon Project has been hammering away at since their inception two years ago. And having received over $30M in funding thus far, Rubicon has been on a rampant growth curve this year. In June they began expanding their operations internationally. For publishers wanting to get the most revenue for their inventory while not needing to constantly swap out code and manually crunch the numbers, Rubicon Project has emerged as a top contender. With one implementation it easily allows publishers to manage multiple ad networks and optimize them for the highest payout. And with so many networks competing for so many publishers, this is good for the ad networks too. Of course, Pubmatic, Hubpages and Yieldbuild have also been competing in this category, but the team at the Rubicon Project has executed better than anyone else in this space.

Some have suggested Google’s decision to enter this space is a bad thing for the Rubicon Project. I disagree. Google’s recent decision is the best thing that could have happened for three reasons:

First, it makes Google look defensive, which not only validates Rubicon’s model, but shows investors that they’re onto something. Even Google’s YouTube video on how the process works sounded a lot like Rubicon’s pitch from a year ago. This should make it easier for the Rubicon Project to raise a new round of funding (if they even need it) and/or gain the attention of potential acquirers. It is clear that Rubicon has made enormous traction in an area that a top player now wants a piece of.

Second, it gives the Rubicon Project a new platform from which to speak to ad networks. Let’s face it, Google deals directly with lots of top-tier advertisers and they just won’t be able to convince the networks that they’ll choose network ads over Google’s current blue-chip inventory. Google’s balance sheet would prevent it 9 times out of 10. But since Google is now stoking publishers on a new way to deal with ad networks, it gives the networks a choice: work with Google, continue spending lots of money to out-advertise your competitors, or work with a “network consolidator” like Rubicon. It plays very well into Rubicon Project’s goals to expand and bring more networks into their fold.

And lastly, Google’s momentum in this space only makes the Rubicon Project look more valuable to potential acquirers and large-scale partners (I’m looking at you Microsoft, Yahoo, CBS, CNET and AOL). The non-Google players definitely wouldn’t want to participate in Google’s new program, and the more successful Google is, the more these other players may start thinking about increasing distribution through either a partnership or an acquisition. This puts the Rubicon Project in an amazingly good position.

Of course, there are a few unknowns here. Its hard to say how much traction Google will make with the publishers, or how this might negatively impact an AdSense publisher’s decision to give the Rubicon Project a try. Its also difficult to know how this might help or hinder Rubicon’s ability to move up the value chain and work directly with advertisers (something Rubicon has made clear they won’t do, and understandably, since it would hurt relations with ad networks). Since Google is now working with both advertisers and networks via AdSense, will it change Rubicon’s prospects?

One thing is clear… Google saw Rubicon’s growth as a low-end disruptor as a threat and they responded on Wednesday by opening up their AdSense program to third-party ad networks. For the Rubicon Project this creates new investment opportunities, a stronger proposition to the ad networks, and new value in the eyes of potential acquirers and partners. Especially now that AdSense has crossed the rubicon…

(disclosure: I used to work with Rubicon’s VP of International)

(another disclosure: Three weeks ago, TrendSlate applied to Rubicon’s publisher program. We were denied. )