Update: A reader has informed me that, even though Russian isn't yet listed in the KDP supported languages list, the KDP support team no longer blocks Russian language ebooks. Thanks, Vladimir!
There has been no official announcement from Amazon on their plans for the Russian ebook market, but I do know that Amazon has had a presence in Russia since at least April 2013. That's when they hired Arkady Vitrouk, the former CEO of the Russia's Atticus Publishing Group, to head the Russian Kindle Store.
Amazon has never been one to broadcast their expansion plans but they have in the past dropped hints. For example, the Kindle Touch shipped in 2011 with support for Italian, Spanish, and Brazilian Portuguese, and the Kindle Paperwhite launched in 2012 with support for Chinese and Japanese. All of those countries eventually received a local Kindle Store.
This new support for Russian is almost certainly a sign of Amazon's intentions, just like last month when Amazon added support for a couple dozen additional languages in the Kindle Store, including everything from Afrikaans to Icelandic.
I have no guess as to when Amazon will launch the Russian Kindle Store, but I suspect that it will happen as soon as they can make it happen. There already are two international ebookstores in Russia (
iBooks and Play Books); Apple and Google both launched in Russia in late 2012. Kobo is also interested in that market, and there were also hints that Barnes & Noble was interested in expanding into Russia, though that does not seem likely at this point.
Update: Apple hasn't launched in Russia; they support the Russian language in iBooks but do not yet sell ebooks in that market.