SecondMarket - sale of private equity

I attended a presentation put on by Second Market last month which offered up a variety of views on these secondary sales from a panel of VCs, attorneys & institutional investors.
My take away is that the current activity we are hearing about is common stock being purchased by institutional investors. Due to the high transaction costs by platforms by Second Market and the minimum transaction sizes imposed by "platforms" like them , the size of the transactions need to be relatively large to make sense to the seller. Since the transactions are between the shareholder and the purchasing entity, no proceeds are going back to the company. I did not get the sense that we are on the verge of a true alternative market where a company can use one of these platforms as a capital raising method. Many other factors, SEC rules (500 shareholder limit, general solicitation prohibition, Rule 144 holding periods) among them, would need to evolve for this to happen.
However, as the time to an IPO or exit gets longer, company's are having to deal with the 10 yr life of a traditional stock option as well as the employees, founders & angels desire to obtain some kind of interim liquidity. This is likely where structured programs offered by platforms like Second Market & others could come in to play.