They actually have a story behind that x.com
domain. According to Bob Schwartz (President of Magento, who I very briefly met last year) Jeff Bezos (Founder of eBay) nabbed that domain many many years ago and has always been looking for a way to use it for some kind of game-changing ecommerce type thing, which is why they acquired Magento.
From a biz/dev perspective, Magento is great, it's perfect for customers as it provides loads of great e-commerce functionality out of the box and an easy to use admin interface. Developers love it, as it's all theme/framework/cms based, generally you just configure it's options and do mostly front-end dev.. you don't do a lot of back-end unless your customising features. As it's open-source based it also has a huge development community with thousands of plug-ins and modules for added feature/functionality, not dissimilar to Drupal or Wordpress.
Surprised it's not widely used in Aus, though Aus seems to be 3-5 years behind the UK, Europe and US in internet regards.