You know, sometimes you never fully appreciate electricity until you don't have it for a few days. Thankfully, the crews here in Raleigh, NC, USA have done a good job of restoring power pretty quickly after an ice storm this week, and now I can get back to feeding my online habits.
This thread has certainly gotten far off topic, but who am I to try and put it back on course?
As much as many of us would like a standard format for importing/exporting data for D20 games (I think most of us see beyond D&D), I doubt that an accepted standard will ever be reached. As Chris points out, and I paraphrase, developers are egotistical, vain, and have a firm belief in the superiority of their own design.

Even an XML format put forth by WotC, while it would be accepted, would almost certainly fall short in the eyes of many third party developers. The ever growing body of D20 games only complicates the matter.
Most developers will probably try to support WotC's XML format in some form or another. They'll continue to keep their own XML or proprietary format (nobody is going to toss out that much work). They'll also probably support some of the other widely used third party programs' XML formats. As DarkWhite pointed out, XSL provides the means for 'transforming' an XML document from one format to another. The only trouble is that it's up to the developer to create XSL documents for each format he wants to support. I can only think of 4 third party tools in 'wide' use that I would even consider worth the effort to support. That's a lot of work to support each of those tools, and four isn't even that many!
I've touched on ontologies with other discussion groups before. It looks promising and well suited to this soup bowl we have with the D20 system from the white papers I've read.
Ultimately it's the end user who benefits. They should have lots of choices and not be penalized for choosing product X when their friend chose product Y. The tools for improving software interoperability have come a long way in the past decade. It's good to see that developers are taking advantage of them.
A standard? Doubtful. A mix of support for a couple of different formats is most likely.