As the English version of Pravda (a leading Russian newspaper) reports,

Russia's Federal Security Service closes down Pravda.Ru's Russian version over Danish caricatures

The visitors of Pravda.Ru website have been deprived of a possibility to access the website and its materials today. The main Russian version of the Pravda.Ru portal has been closed today. The message, which appears on the blank white page, says that the site has been closed down pursuant to the requirement from the Federal Security Service

I've checked this myself, and read the original Russian-language explanation from the editors; the English-language explanation is here.

Ostensibly, the reason for the closure seems to be Pravda's publication of the Danish caricatures — but Pravda denies ever having published them. (Note also that some of the Pravda Russian-language material remains accessible through the explanation-from-the-editors page, so I'm not sure just how much of the Pravda site has been shut down, though the blockage of the main page is indeed burden enough on the newspaper's operation.)

Thanks to reader Anton Pribysh for the pointer.