> > Exactly what trademark infringments are they worried about?
> 
> If a company has a trademark, but it does not take action to 
> prevent that such trademark grows into common use for a class 
> of products (instead of for their specific product) they 
> loose the right to that trademark. Happens very often, IIRC 
> for instance Philips 'TL'.

from http://en.wikipedia.org/wiki/Trademark :

Further, if a court rules that a trademark has become "generic" through
common use (such that the mark no longer performs the essential
trademark function and the average consumer no longer considers that
exclusive rights attach to it), the corresponding registration may also
be ruled invalid.

For example, the Bayer company's trademark "Aspirin" has been ruled
generic in the United States, so other companies may use that name for
acetylsalicylic acid as well (although it is still a trademark in
Canada). Xerox for copiers and Band-Aid for adhesive bandages are both
trademarks which are at risk of succumbing to genericide, which the
respective trademark owners actively seek to prevent. In order to
prevent marks becoming generic, trademark owners often contact those who
appear to be using the trademark incorrectly, from web page authors to
dictionary editors, and request that they cease the improper usage. The
proper use of a trademark means using the mark as an adjective, not as a
noun or a verb [2] [3] [4], though for certain trademarks, use as nouns
and, less commonly, verbs is common. For example, Adobe sent e-mails to
many web authors using the term "photoshopped" telling them that they
should only use the term "modified by AdobeR PhotoshopR software."
VeriPic likewise sends e-mails to reviewers using the term "VeriPic your
digital photos" telling them that the proper usage of the term is
"protected by the VeriPicR Digital Photo LabR secured photo database
software." Xerox has also purchased print advertisements declaring that
"you cannot 'xerox' a document, but you can copy it on a Xerox Brand
copying machine." Such efforts may or may not be successful in
preventing genericism in the long run, which depends less on the mark
owner's efforts and more on how the public actually perceives and uses
the mark. In fact, legally it is more important that the trademark
holder visibly and actively seems to attempt to prevent its trademark
from becoming generic, regardless of real success.

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