Having said that, all they are doing is providing the same Investment banking services to companies that they always have, just now, they are offering it to private companies.
Think of it as a cover your ass approach, if companies decide not to go public, GS still gets a piece of the action, and if they do go public then its an easy pick for GS to lead their public IPO's as both sides already know each other.
They are also trying to lead the charge in allowing people to invest in private companies through investment vehicles that look similar to funds( ie pooled capital that they raise and invest for share holders).
With companies staying private for so long some people, and I'm starting to become one, now think that the day of the publicly traded growth company are coming to an end and that companies will go public once they have matured into value stocks.
This is evidenced by the markets are loosing patience with companies like Groupon, Zinga, Yelp and my personal whipping boy Twitter. Come on twitter, get your act together, you wont' be around much longer if you continue on like this.