Fresh off their acquisition of Others Online, the Rubicon Project just closed a $9M round of funding. $6M came from Peacock Equity, the joint venture between GE and GE’s NBC Universal, with the remainder provided by existing backers Clearstone Venture Partners and Mayfield Fund.

This brings Rubicon’s total venture funding to $45MM, a sizable amount of capital raised amidst the global economic downturn. This latest round of funding will likely be used for additional acquisitions by the Rubicon Project to enhance targeting, relevancy and distribution for ad networks & publishers.

Just last week, the Rubicon Project acquired behavioral-targeting firm Others Online. The Others Online acquisition enables the Rubicon Project to add a layer of behavioral targeting between publishers and ad networks, placing Rubicon at the cutting edge of a shift from contextual targeting to one based on actual user behavior. This makes the Rubicon Project a serious player in terms of both the targeting AND distribution.

And it is that combination, along with Rubicon’s effective model of solving pain for both publishers & networks, that likely led Google to enter this market last month. We predicted at the time that this is actually a very good thing for the Rubicon Project.