Surely many users of mac os x have encountered problems displaying Russian fonts. For example, spaces between letters. An example and one of the solutions to the problem is under the cut.
Example problem:

For the solution we will use the wonderful tool of the web developer - Opera DragonFly. Open it through Tools-> Advanced-> Developer Tools, click on the problematic text and look at the style:

Yeah, the courier font style is used. Go to Preferences-> Web Pages and look at the monospace font-> Courier font is used. Let's see what the Font Book tells us about it:

')
Yeah, something's wrong with the font. Unfortunately, I still don’t know how to cure the Courier font, but you can check another fixed font - Andale Mono and make sure that Russian is displayed correctly in it. So, let's go back to Opera, choose Andale Mono as the monospace font and voila, everything works:

I hope my advice at least helped someone. Transfer to Opera blog is not enough, alas, karma.