Yale and Harvard got creamed in their non-liquid alternative assets. The basic idea was that by using alternative assets with 'stock-like' returns, they could further diversify their portfolio. Unfortunately, when correlation went up and they couldn't get out of their holdings, their portfolios took a hit.
It is a great idea, and I have had some success in replicating it ... but using liquid ETFs and ETNs for some of the alternative stuff. You can even find some funds that track private equity, etc...