I am only knowledgeable about the subset of the Russian fandom I directly interact with. The main slash archive is http://barrayar.slashfiction.ru/. However, the Cyrillic encoding there is nonstandard, so people might have trouble with it. It hasn't been updated in a little over a year.

Current fandom activity is centered on jetta-e's journal (http://www.diary.ru/~jetta-e/)

The most prominent work in the Russian fandom is probably the slash novel "Победивший платит" (http://barrayar.slashfiction.ru/pp.htm or http://barrayar.slashfiction.ru/pp.zip), set just after the First Cetagandan War, in the Cetagandan Empire, starring OCs.

For people interested in reading translations of Russian fic into English, there's a good selection on the Winterfair master list. Some other translations have been done as well.