Here's a quote from another hn user robert_foss from the discussion on the Apple / Imagination Technologies thread.
'In the GPU space it is impossible to not infringe on the IP of other vendors.
In fact it is the major reason GPU vendors give for not having an open source driver. I have spoken to the CTO (Jem Davies) of ARM about the GPU drivers and open sourcing them more than once. And every time I've gotten the reply: "No, we can't, it opens us up to IP infringement suits."'