graeme_p - 5:11 am on May 1, 2010 (gmt 0)
I can, however, win a trademark infringement suit against someone who tries to sell and operating system called Windows
Bad example: Lindows was allowed in most countries (including the US), but they lost the case in enough to force a change of name. X-Windows is available everywhere.
One problem with TM law is that it is often difficult to know what is OK and what would be a breach.
That said, I think you are right that Rosetta Stone has a pretty strong mark as far as language learning software goes.
Try to create a clothing item on CafePress that uses the word "caution" - they won't let you because some guy who loses every suit he files, has filed against them and it isn't worth it for them to fight it.
Good to know the law works so well that you can effectively win with a case that has no merit!