So much hate in this discussion
Firstly to all the commenters stating this is an issue of copyright (OMG they trying to copyright the dictionary!!!) or 'patent' the word are clearly confused - this is an issue of trademark not of any other protected asset.
Second it is perfrectly acceptatble to have a trademark for a word that is already in the dictionary, provided that you can make a case for it (as a commenter above noted, it hasn't stopped 'Windows' being afforded protection).
Thirdly in order to enjoy the luxury of having a trademark it has to be defended else it might pass in to general language. That's why Google or Tivo are probably not happy that their trademarks have effectively become verbs - it then makes defense of your trademark much more difficult.
Finally the comparison with POD shoes is a non-issue. The trademark can only be rigourously defended against other marks that might be considered competitors or are in the same market. If POD shoes suddenly made some kind of shoe based MP3 controller, that would be interesting. A relevant example is also the Apple computer versus Apple records dispute - in that case there was considerable debate about whether their activities overlapped or could be confused.