Two updates have already been made for
biblatex since we tested compatibility problems of TeX4ht with the package last. This time, except for one change of the string,
URL, which was hardwired in previous versions, becoming a localization string, all the remaining changes relate to
biber, the bib database processor. None of these have any bearing on TeX4ht. However, a thorough run of all example files in the package bundle has been done and could not find any problems in generating HTML output identical to the PDF counterparts.
The test suit is available here as a composite tarball. The version of
biblatex.4ht used for the tests which is the same as in the current version of TeX4ht distribution is also available here in case someone needs it.