TLDR: Pixel and Tonic a company that makes Expressionengine addons (arguable the two most popular plugins) created it's own CMS - "Craft". This rather annoys off Ellis Labs (makers of Expressionengine) so much that they add the functionality of P&Ts 2 main addons to the next release of Expressionengine in retaliation.

Although system makers (operating systems, content management systems whoever) regularly incorporate third parties application's functionality into their systems. I've never seen one launched with the message that it was created to punish a third party.

I can't say I blame them. FTA, P&T tried to announce their competitive product at a EE conference using A/V equipment paid for by Ellis Labs. i don't know much about EE and P&T, but if true, that was a dirtbag move on P&T's part.

Plus, Ellis Labs makes a good point here:

"Our customers do not have to worry whether or not Pixel & Tonic can develop and support something as complex as a publishing platform and still maintain the time and interest required to continue offering and supporting add-ons for a competitor’s product. It is a sincere and realistic concern that many of you have shared with us."