Intellectual Ventures, at least, is structured as tens of thousands of theoretically independent corporations each owning one or a small number of patents. The idea is to have as few assets as possible in the suing agent so that there's no point in countersuing for any misconduct in the proceedings like barratry: http://en.wikipedia.org/wiki/Barratry_%28common_law%29 Misconduct may not be the best phrase, since there are a million ways to be liable that don't involve wrongdoing, but the idea is the same - you want to construct an artificial you that's as poor as possible so you have that much less to lose.

It's why the RIAA does the suing rather than the record companies themselves - you've got a long lawsuit to prove that anyone pierced the corporate veil before you can get anywhere near touching the entity with the actual monetary stake.

IANAL, so don't go too crazy with this.