We need a policy on trademarked images to be clearly defined, and if
there is one, it needs to be publicised somewhere prominant - are
trademarked logos which claim to be under a free license really free, or
are they violating copyright? Case in point, I've just deleted
http://commons.wikimedia.org/wiki/Image:Exquisite-redhat.png and moved
it to en: per an offical request from Redhat.
Personally, drawn logos like this are unacceptable for commons, and
contrary to established practise which is to use them under fair use
on the en: Wikipedia.
I am inclined to also count in this category photos of an object
bearing a trademarked logo in which the whole intent is to picture the
logo. Quite aside from trademark law, such images are likely to count
as copyright infringement if the subject is copyrighted, which
many/most logos will be. Logos first used in the United States when
the law requiring a copyright statement for copyright protection was
still in effect may not be protected by copyright law, but I'd say we
should simply be safe and avoid all marginal cases.
Aside from those cases, I would personally not bar an image from
commons because a trademarked logo or indeed other trademarked aspect
appears in it.
Any photo in which a trademarked item appears in it MAY not be usable
in all commercial contexts, but I do not think that commons should
only consist of images safe to use in commercial advertising.
In an encyclopedia context, or any reference work, such appearance of
trademarked items is quite legal, I believe.