Facebook hasn't IPO'd because there is no value for them to do so. They have enough liquidity on the secondary markets to keep employees happy and they are able to keep investments coming through alternative means. All an IPO would do would be to increase their paperwork.

Don't forget an IPO would also require Facebook to disclose numbers they'd rather not while they still have liquidity. That's another major reason.

Indeed, plus legal liability etc. etc. etc.

The longer they wait, the better it might end up for the rest of us. The SEC suffered major embarrassment when Americans were dropped from Goldman's (?) recent Facebook investment vehicle and is at minimum looking to revise the current rules which date back to 1935.

That's not going to fix SarBox, but maybe, just maybe that sort of bad attention/publicity will help.