Yahoo! News is reporting that African clawed frogs (Xenopus laevis) have taken up residence in Lily Pond, part of San Francisco's Golden Gate Park. While Lily Pond is not exactly a prized natural habitat, the fact that the frogs are there means there is a risk that they could escape to more natural bodies of water in the area.
Once a popular pet for Californians, African clawed frogs have been banned in that state, but can still be used for research or educational purposes. Officials suspect they were introduced intentionally by people who did not want them to be killed. While the population has been known about for almost a year, a lack of funding has delayed plans for eradication. Be sure to click on the "AP Photo" in the story to see a drawing and more information about the species.
(Thanks to a member of the ALIENS-L listserver for pointing out this story.)