Google is continuing their attack on international spam, with Matt Cutts announcing they had taken down two Polish link networks.
There is some speculation about which two link networks have been taken down, however it will be a couple days before we know for certain which ones were penalized unless networks themselves comment on it.
Buying and selling links seems to be quite common in Poland, so we could see some dramatic changes in Google's Polish search results in the coming days.
Google also added a reminder blog post to the Polish Google blog, alerting webmasters about unnatural linking and how to do a reconsideration request. This is similar to what they did for French webmasters, when they posted a reminder about buying and selling links in the French webmaster help forums.
After Google was active in taking down English language link networks late last year and the beginning of this year, Google now seems to have focused on international link networks. While Cutts specifically says they aren't done with Germany yet, they penalized one German link network earlier this month shortly after they took down the French network Buzzea.
Affected Polish webmasters, or those who suspect they are possibly caught in it, should check their Google Webmaster Tools accounts for the next week or two, depending on how long it takes the penalty to appear. However, you can be proactive and remove any links you believe will be impacted off of your own sites, and request webmasters to remove links that point to your site.
With Google being really focused on the problems surrounding link networks, we should definitely expect more to be taken down, both English-language and international.