So for example, you have:
Open bitcoin.po with poedit, do Catalog->Update from sources. It looks for the sourcecode up 3 directories (..\..\..) from where bitcoin.po is.
This updates your existing .po file you already worked on and adds any news strings. It may try to match close strings, so check things over and make sure it didn't make any bad guesses.
Make sure you use the .po file I uploaded to SVN or in a release, because I always fix up at least a few things. I'm attaching your Russian one to this message.