The academic community has been working with semantic indexes for quite some time. I know many of those involved. The real question is whether they have developed something fundamental recently.
As for performance, yes perhaps they have some innovations. But with NLIs its usability that matters the most in the end.
At a more technical level I think the question is how expressive/consistent is the logical form they are mapping too. If they have developed a parser that maps to an LF that can lead to actual inferece then that would mean something. But then they need an open domain strategy to actually reason over such expressions in a meaningful/useful way. We will see.
Somewhere out there in the libraries are the computing equivalents of transparent aluminum, but you can barely get researchers to look at this stuff, let alone Joe Javahead.
As for you comment about researchers not being aware of the literature, I agree 100%. I review from time to time and the number of papers that are reinventing the wheel (and doing so in a sloppy way) is staggering. I think the problem is that too many researchers are just concerned with building up as many papers as possible to beat the tenure clock and/or to impress their rivals.
Evaluators somehow need to stop bean counting publications as a measure of merit. The problem they face is they don't know how else to evaluate...
Plus, when computer science was new, a lot of crazy stuff was being researched; nowadays the academic research seems pretty close-minded.
PARC has certainly done brilliant,pioneering work in many areas. What most people miss is that PARC had many deadwood/unsuccessful projects (and people and worthless papers ) in its time.
I know nothing about what exactly PARC licensed to Powerset, but without more data, I wouldn't automatically assume that it provides an edge.
My understanding is that the technology Powerset got from Xerox is a production quality, multiple language parsing system with a language-independent core, with the long development time being due to the engineers being allowed to work on the problem until they had solved it to their satisfaction.
Of course, all of my information comes from the above-mentioned presentation, so a large pinch of salt is almost certainly required. :o)