Hi Tomasz,
as far as I know, Mediawiki 1.17 seems not being compatible with the DumpHTML extension (we have here at least a problem with CSS files). Consequently, nobody (me included ;) will be able to make HTML dumps with an uptodate Mediawiki PHP code as soon as this released will be rollouted on WMF servers. Do exist plan to avoid this future issue?
Regards Emmanuel