There are only two parties hurt by this:
1. The premiere clients of Goldman Sachs and Morgan Stanley who bought into the lie that FB should trade at >100:1 P/E; and
2. Facebook.
(1) I don't care about. (2) is the interesting one. You'll note that I don't include the employees in the list of injured parties. They're largely in a lockout anyway (I assume?). Whether it opens at $38 and drops to $30 or starts at $20 and climbs to $30 is of little consequence.
Facebook strategically seems concerned with only two companies: Google (disclaimer: I work for Google) and Apple, both of which have established, proven businesses and strategic assets in Internet and mobile going forward.
Facebook is a platform company without a mobile platform in a world becoming increasingly mobile.
Facebook has a lot of cheerleaders, optimists and pundits all backing this idea that the potential of all this data is huge, so much so that I believe they started to believe their own positive press. It's an easy trap to fall into.
But make no mistake: this is bad for Facebook. Sure some investors, Zuck and (maybe?) some employees made a few more dollars but Facebook doesn't need the money and neither do most of the investors. But that's incredibly shortsighted.
Facebook's ability to retain and attract talent and make stock-based acquisitions is in large part determined by the health and outlook of their stock. If they'd IPOed for $20-25 and jumped to $30 then they would have a lot of momentum behind them.
Instead the press is "how low will it go?" What kind of position is that to be in if, say, you're trying to negotiate a $1B+ stock-based acquisition?
Anyway, I'm glad about this drop. Not out of any kind of schadenfreude but because the market is acting... rationally. These P/Es were never justified and instead of not mattering and the stock skyrocketing anyway (which would happen were we in a bubble, which we are not), the stock is seeking a more appropriate level.
This is good for us, the tech industry and the market and the fact that some choice clients of Goldman Sachs and Morgan Stanley got bilked along the way is just gravy as far as I'm concerned.
EDIT: to clarify, I don't really have a position on what the appropriate level is other than $38 is and was too high. It could still well go lower than $30.