Fun fact: mtgox (the Bitcoin exchange) originally stood for "Magic: The Gathering Online Exchange" and was a site for buying/selling "Magic: The Gathering" cards.
The insinuation is that the current site is somehow tainted by it's use back in 2007, but as far as I can find [1] it was never anything but a "coming soon"page.
It's fairly common to ridicule it's current use in the Bitcoin world by associating the currency exchange with playing cards.
These people are not my close friends (I occasionally contacted them by IRC or E-mail for support, probably more often their employees) but
I am pretty sure that Jed was the person who started the business, and he sold it to MagicalTux. This would indicate that it's a coincidence that MT in MagicalTux is like MT in MtGox. Maybe MagicalTux chose his nickname for this reason.