This is an issue people commonly raise. The trial URL gets indexed and there's currently no way to disable it or 301 redirect it to the actual site URL. You should go to Google's Webmaster tools and specify the primary domain for that site and you may also take a look as rel="canonical" - http://support.google.com/webmasters/bin/answer.py?hl=en&answer=139394. I belive that our dev team has started work on this and I belive that we should see the 301 redirect feature for those URLs soon.
Hey Mario, Engineers made changes though to stop all that. Issue lies with if someone has incorectly linked the site to people with that URL or the site itself still has that URL around the site. (which I think it does)
You need to get that all fixed up from the site, do things like the webmaster tools like Mario said and google bots will start not finding it, realise your other URL's have more weight and stht will all fade off. Canonical is not a directive and not as effective cross domain as it is for its real role with within site URL prioritisation.