Huge news for Facebook: Goldman Sachs is investing $450 million in the company at a $50 billion valuation, the New York Times' Dealbook reports.

This as Facebook starts to threaten Google as the most important site on the Internet.

Goldman's investment comes alongside a new $50 million investment from existing Facebook investor DST, the Russian investment firm that has also invested in Groupon and Zynga. And Goldman has the right to sell up to $75 million of its stake to DST, the NYT's Andrew Ross Sorkin and Evelyn Rusli report. (They also point out that DST has made out amazingly on its initial investment in Facebook, around half a billion dollars at a $10 billion valuation.)

Also as part of the deal, Goldman will help raise up to another $1.5 billion for Facebook at that $50 billion valuation, according to the NYT.

And, of course, this puts Goldman in the lead to run Facebook's eventual IPO.