Hallo Russia. I have been using Yandex Maps through the Mapstraction API. It was tricky to join since the captcha required a cyrillic keyboard, but i made it ok.
I got an API key and my Yandex map application worked at first, but when i uploaded a new version to the same URL it stopped, I am guessing this is a 'http referer not valid' message...
You can look at my app...
and do 'view source' (anywhere outside the flash application div) to see the api key i am using