Just as "e-mail" means electronic mail, e-rony means "electronic irony". E-rony occurs when a website changes something that originally attracted people to said website in order to be more like a perceived internet rival with considerably fewer users or supporters, thus losing it's users to it's rival and ensuring the rival's success. One example would be google abandoning it's formerly uncluttered, user friendly design to become more like bing. Adding a fade-in, an "everything" sidebar and background images and ignoring user complaints. Thus encouraging it's users to stop using google and seek out an new search engine. Another example would be myspace going to it's "2.0" version and not allowing users to switch back to a true "1.0" format (the 2005 version). Done to compete with the then less popular twitter and facebook. Prompting users to kill their accounts and migrate to twitter and facebook.
Yeah, have you seen the changes google made to it's home page today to compete with bing? Oh, the e-rony.