Would just like to point out that prior use of a title doesnt mean you own it, since you can only own a title if you fork out the money to have the name registered. So im affraid WOTC **would** own the title planeshift, there products name might be actualy more than just Planeshift but often companies will register the individual words of there products as well ie, \"Magic\", \"Magic the gathering\", \"Planeshift\" and \"Magic the Gathering: Planeshift\".
You also have to be carefull since some owners of copyrights are fanatical in there protection, point in case would be Anne McCarthy and the Pern books, heck i could get into trouble even mentioning those words on the net. They are so tight with there copyright they will and have filed law suits against those that even write fan stories or do \"Pern\" style dragons in there artwork. Although this behavioure seems thankfully rare. But being free and open source means nothing if those sueing you have the best lawyers and a ton of cash to back them up.
Be carefull
ps:- a piece of software i use had to have its name changed only a few months ago since a company bought the copyright to the name and ordered the software maker who is just a guy makeing the programme for fun and a little profit, to change the name or else... and hes had the name in use for 5 years now, sept he didnt have it registered as a copyright.
If you realy want to avoid trouble you should register/copyright the trademark, although Im unsure of the price to do so. Its not THAT expensive, but worth it in the end.
