It actually sounds like the opposite was ultimately decided by the supreme court. Two lower courts decided in favor of the DB owner (in this case analogous to Craigslist), but the Supreme Court found that the database did not meet creativity requirements to fall under copyright law (in the example, a company was not allowed to claim copyright over a database of phone listings in alphabetical order).

Applying this example to the Craigslist situation (in a decidedly IANAL fashion), Craigslist would have to be able to argue that the manner in which it "selects", "coordinates" and "arranges" its data is creative and unique enough to be protected by copyright law, and furthermore that PadMapper's use of the data infringed on that specific creative selection, coordination, and arrangement of the data (since the data itself is still not protected by copyright).