Daniel-
IIRC from my business law classes, registration is only needed before seeking actual legal action in court (just as with copyright infringement).
According to
http://www.iusmentis.com/trademarks/crashcourse/procedure/
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Unregistered trademarks
It is worth noting that some countries, in particular the United States, also provide trademark rights for unregistered trademarks. The mere use in commerce of a particular sign can turn that sign into a trademark, which others may not use for the same types of goods and services. Such unregistered trademarks are sometimes indicated with the suffix TM, while registered trademarks are indicated with the famous R in a circle R.
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(Note that the name Wikipedia has neither a TM nor an (R) next to it.) Are we on solid enough legal ground with an "unregistered trademark" to send nastygrams to some guys in Russia? I highly doubt it. And I wouldn't want it to be any other way. Trademarks are evil enough as it is.
Regards,
Erik