Meanwhile, technological developments-in general, the personal computer, the Internet, and e-mail, and in particular a data technology called XML-have made it possible for political organizations to have much richer information about individual voters. It used to be that you could find registered Republicans and registered Democrats, or heavily Democratic and heavily Republican precincts, but that was about it; now, because XML cross-references previously incompatible databases, you can easily blend electoral and commercial information (gleaned, for example, from mail-in product-warranty cards) and identify the people in Republican precincts who are most likely to vote Democratic, or Republican voters who can be moved by a specific appeal on one issue but not by the Party's main over-all TV-ad pitch. (In the 2002 Georgia governor's race, the Republicans were able to use pro-Confederate flag material with rural voters without the major media markets noticing.)
Weird. XML is really just a syntax for marking up text so that it has a tree structure. It's basically identical to Lisp s-expressions, which have been around since the late 50's. What the writer really means in the above paragraph by "XML" is "techniques for integrating heterogeneous databases"; XML is only the tiniest piece of the enabling technology for this work. Still, it's interesting to hear that political consultants are using XML to produce integrated pictures of voters' behavior.
The Confederate Flag business is notable too, if only in the predictable "Well, yeah, there's the Republicans pandering shamelessly to people's worst instincts again" way.