Following the lawsuit that eBay filed against Craigslist, the company publically criticized eBay for their actions. Ebay's stance remained unchanged, and they showed no signs of dropping the suit. As a result, now Craigslist has sued eBay, claiming that the giant company was using corporate spy tactics to steal trade secrets of the inner workings of Craigslist.
That's a pretty harsh claim, and one that Craigslist will have difficulty proving. They also claim eBay has violated copyrights owned by Craigslist and accuses them of unfair competition, misleading advertisement and fraud, all in an attempt to boost the Kijiji site. Interestingly, they claim eBay had an internal project named "Craiglist Killer" that was specifically designed to boost rival sites. It would seem obvious that eBay would seek to acquire Craigslist in order to grow, but obviously the owners of the smaller site do not want that to happen.