Social networks, mashups, and... Trademark Lawsuit?

In reading the material for this past class, I saw a link to a mashup that was of particular interest to me (I think on the IBM article). It was called diggdot.us, and it simply mashed together all of the popular stories on Slashdot, Digg and del.icio.us/popular. Since I am a regular follower of both Digg and Slashdot, I figured it was worth checking out. After clicking the link, I found out that they were forced to rename themselves, and were now known as doggdot.us. Apparently Digg had sent them a cease and desist letter over their use of the name "Digg" in their DNS entry/name. Kevin Rose (Co-founder of Digg) posted on the Digg blog the following:

A while ago our trademark attorney approached us and was concerned we could lose the name 'digg'. I had no idea this was possible as we had already filed for the trademark. Apparently if you don't enforce the TM (meaning not let other sites use it), we run the chance of losing it... which would suck. The last thing we want is to lose our name.

So what to do...

We don't want to shut anyone down (not even the clone sites), all we ask is that you avoid using the name 'digg' in your website names/domains. We're looking to see if we have any other options.

Digg on,

Kevin

So, in order to protect their trademark, they had to make sure no-one else was using the name "digg?" I've heard of that rule before (you need to show that you actively enforce your trademarks in order to keep them), but this case seems a bit extreme...

I mean, Apple hasn't sent C&D letters to any Mac-related web sites with the words "Apple" or "Mac" in their DNS entry/title (i.e. MacFixIt, AppleInsider, Macworld, HardMac, MacInTouch, etc).

But wait, I do remember something like this involving the "iPod" trademark a few years back...

So perhaps the "Apple" and "Mac" trademarks have become too diluted to enforce, but iPod was "fresh" enough that Apple wanted to fight to keep it?

While not directly relevant to social networking, I find this an interesting and relevant, considering if you choose a name (or even part of a name!) for your site that someone else has already trademarked, and you build up a user base, things could go badly if you happen to fall under the magnifying glass of an over-zealous legal department. Remember the hubbub that happened w/ the naming of the Firefox web browser (formerly Firebird, formerly Phoenix) due to similar issues?

I'm really liking these "wild west" analogies when it comes to how things are right now on the Internet...