yandex accounts for around 57% of the search engine market share in Russia. Its by far the most used search engine over there. Google only accounts for a small percentage of searches. optimising for Yandex in the limited experience i've had seems to be all about links at the moment. this might be a bit of a vague description but think of it in terms of Google maybe 4-5 years ago.
I use www.yandex.ru whenever I need to find a crack or a serial number for something... In this field, it is by far better than Google. I also sometimes use it on the rare occasions I don't find what I am looking for from Google and it usually deliveres.
No I still don't know about this anything, but I will try to find some info about this and I will leave here.