Interesting article and an almost coherent Google translation. It certainly answers some of my ??? and when you think about the limited ram (esp. at the beginning) on top of the Cell implementation (though a browser should be able to run by itself on the PPU) you can understand why they went with a (mostly) homegrown browser. At this point though, one would think that pride might be holding them back from dumping it and going with something else. Other thoughts:
Since it is homegrown there's no reason to dump it now, they could offer a new browser as a PS+ upgrade and keep the other as the default and allow it to deprecate over the rest of the console life.
With the limited memory in mind, jeff_rigby may be right in that if they wanted to make available the gddr ram you would want that handled by the rsx, so using ogl make alot of sense.
It may have been the translation, but they seemed to indicate that the psp browser is homegrown (ish) too.
Steam uses webkit also, along with Google chrome, and of course with its origins in MAC OSX (on a PPC), as they may not have to ditch all their underlying work done on the current browser, there's alot of synergy moving in that direction.
One of the interesting things to consider is what the @#$% happened with 3.5? It was certainly shaping up to be a major release, but when they had to delay alot of it why even release? The answer could be that thye were still able to put out the underlying structure of a new platform and thus still meet commitments to Steam, Hulu, ESPN et al. It sucks if they're going to come out with the rest of the update in a month or so, but cross game chat would sooth thing over...................for a week..........maybe..............