Public sector websites and web standards
Peter Krantz at Standards-schmandards has performed a mass validation of government websites in the United States. The result, as expected, is not good. Only 14 of the 546 tested government websites use valid markup. More info on the test and the tools used is available in Government web standards usage: USA.
A similar test has been conducted for Swedish public sector websites, with only slightly better results: 60 out of 1015 sites use valid markup. The test results are shown in Resultat från tillgänglighetstest av webbplatser inom offentlig sektor (in Swedish).