Neither the US and Canada require registration for trademark enforcement or validity. I have been using Twisted Melon as a trademark since 2004, every logo or document page clearly labeled with a "tm" on at least the first instance. Registration process however, is under way in the US, the most important market.

And "Twisted Melon" is not necessarily the only trademark I had in mind when I posted the original topic.
In the UK, yes, Jay Grant trademarked Twisted Melon after I had started using it prominently on my website and after I wrote my blog post about the name and mark in 2006. I knew of his club DJing back in 2006.
Thanks for the feedback guys. I do value your opinions, but I did start this thread looking for feedback of a technical nature, not wanting to get into a philosophical nor moral debate.