The "Save as type:" drop down list in the "File->Export..." dialog does NOT contain "MediaWiki (.txt)". Also, selecting "File->Send->To Mediawiki..." brings up an error dialog: "The MediaWiki export filter cannot be found. Choose Tools-XML Filter Settings to install the filter, or use the setup to install the component.". Note that the Mac version exports to MediaWiki without problems. Tested on Windows 7 Professional, Java 6 Update 31.
THanks for your input
Silvio: about the "Send -> To Mediawiki", it should work from future LO version 4.1.6 or 4.2.3 (cf fdo#69925 in See also) About the dialog, MediaWiki (.txt) appears in export dialog. Put it at RESOLVED/WFM Don't hesitate to reopen this tracker if you still encounter one of these 2 bugs.