The thing to keep in mind with trademarks is that if the owner of a trademark stops defending it, then they can lose that trademark.
Since HaidaBucks is similar to Starbucks and is in a similar field (both are restaurants/cafes), I can understand why Starbucks is threatening legal action. Whether or not it'll go anywhere is another question entirely; I've no idea how similar a name has to be to a trademark before it is considered infringing.
There would seem to be some similarity there. I know that the holders of the Starbucks name are very picky about this sort of thing because a guy in Victoria had a small coffee house called "Starcups" and he had to change it to "mr.beans", because he got several nasty lawyer-letters from a big law firm threatening him with action if he didn't.
Good thing nobody in the Queen Charlottes is building motorcycles and calling them "Haida-Davidsons"...
Now THOSE guys are REALLY serious about their trade name. Boy HOWDY!
Seems that HaidaBucks is gathering support for their battle with the giant Starbucks. They also have a website , good for them not to roll over and give into the pressure. I am sure this will be an interesting confrontation if it does go the distance.