Owen van Natta, the head of business development for Facebook, was pretty cagey on the Microsoft conference call when he was asked about other potential investors in the current round of funding — so it’s not really a surprise to see that two hedge funds have reportedly also invested in the social network at the same head-spinning valuation of $15-billion.

And while this news comes to us from Fake Steve Jobs, we all know by now that FSJ is really Daniel Lyons of Forbes — and as Silicon Alley Insider points out, the same word has also come from FSJ’s real-world colleague Elizabeth Corcoran, who wrote about it on her blog. It still falls under the heading of “rumour,” but at least it’s not just Fake Steve trying to pull one over on us.

In any case, it’s completely believable that two hedge funds would put in $250-million each, despite the high valuation placed on Facebook. After all, the whole sub-prime thing is a goner now, and we know that hedge funds will invest in just about anything. When a Canadian bank invests in Facebook, then you’ll know the bubble is really starting to get over-inflated.

Say what you will about Valleywag (just don’t get Mike Arrington started) but Owen Thomas is a pretty smart guy, and I think he makes a good point amidst all the sturm und drang about Facebook and its market value, and how eBay’s $1.4-billion Skype-related writedown could affect the perception of that value (for more on that, just see this Techmeme thread or the Times Online blog).

It’s true that eBay’s writedown says a lot about the risks of paying bubblicious prices for things, and a $10-billion valuation for Facebook has certainly got more than a whiff of bubble about it. At the same time, however, Owen points out that there are just as many risks in not buying things. eBay is a great example of that too, having tried and failed to buy PayPal early on. And Yahoo has a boatload of missed opportunities, including Google and Facebook.

As for Microsoft’s hyperactive basketball-coach CEO, Steve Ballmer, his remarks to the Times about Facebook being a “fad” are just as likely to be an exercise in talking down the value of something before you buy a chunk as they are a thoughtful commentary on the company’s actual value. Or it’s possible that he really doesn’t get it.

In the end, I think Kara Swisher at All Things D probably has the right read on the situation: Facebook is likely to take some money, at a handsome valuation, but remain independent (unless $10-billion gets dropped off at Mark Zuckerberg’s flat, of course). If nothing else, MySpace shows the downside of being acquired too early.