Today I have found two invalid URLs between Google results.

http://*.tyden.cz/rubriky/kultura/recenze/eoin-colfer-seznam-prani_1014.html

and

http://www.idnes.cz,www.sector.sk,www.tyden.cz/rubriky/kultura/recenze/eoin-colfer-seznam-prani_1014_diskuze.html

Both of them are invalid, i.e. you cannot have "*.tyden.cz" valid domain name. But Google has these URLs in its index.

It looks like some errors that are made somewhow from the orignal URL
http://wwww.tyden.cz/rubriky/kultura/recenze/eoin-colfer-seznam-prani_1014.html

You can find URLs mentioned above in the result: http://www.google.com/search?hl=en&q=tyden+seznam+prani+site%3Atyden.cz

Have anyone already seen such URLs in Google results?

http://twitter.com/hassmanm

Hi Martin
The URLs you mentioned will work in some browsers, for example in IE. The problem here appears to be that the admin of that domain allows all subdomains and returns valid content for them. This means that you can use [anything].example.com (where "example.com" is the domain that you spotted) and it will return a valid page (and may even get indexed). Personally, I find that a bit confusing, but maybe there's a reason the domain is set up like that :-).