In these tough economic times, even trademark lawyers are having to scrape the bottom of the billable hours barrel to keep up with their BMW payments. Sounds like K&L Gates is serious enough that Sparkfun might need to stockpile some legal firepower of their own. I wish them luck.
Most C&D letters these days have about the same legal basis and significance as a grumpy motorist giving you the finger in traffic. One I got a few years ago was filled with dire threats of extreme legal action and consequences despite the small (but significant) detail that the lawyer had neglected to verify that the client in question was, in fact, the legal registrant of the trademark they were writing about (they weren't--it was a registered trademark, but it belonged to an entirely different and unrelated company).
Then two weeks ago, there was Monster Energy drink who was claiming that I had violated their trademark rights by selling products that were "confusing similar" to Monster Energy Drink: i.e., A Monster Movie. Granted, that film does fall into the "late night cable fare" category, but I think their legal team may have just done a few too many late nights subsisting only on Monster Energy.
(Yes, there *was* a picture taken during production where I was holding a can of Monster Energy Drink, but neither that picture nor any semblance of the Monster Energy logo appear in the movie or in any of the marketing materials for it.)