[OriginalSyn]

I can't speak for the USA or anywhere else but in Canada TM means something. Common law trademarks do come with some rights to protect your brand, Registered trademarks come with more. It's been a long time since my IP Law class but I beleive TM allows protection against business in the same industry from using your trademark in such a way that it could be reasonably confused for yours.

[pwaring]

TM still doesn't mean anything in a legal sense - if you're relying on the common law protection then it doesn't matter if you put the two letters next to your logo/brand. Putting TM on doesn't mean you have any protection, and leaving it off doesn't mean you have none.