Mitrax.de have conducted an interview with PowerVR/ImgTec covering various topics about their graphics cores & other... stuff,... things. It's pretty big though with 48 questions & most of them answered (Unless it involves Series 5). Here's one such Q&A;
What is your opinion on virtual texturing? Wouldn't it make sense to use a similar approach on a deferred renderer, especially for the cases where textures flood the local memory?
John: Virtual texturing is an interesting technique & 1 which tile based rendering can take full advantage of, given that a tile based renderer can look ahead a full scene to what textures are required (& in which tile).
Check it out.