As of Summer’15 release, APEX Data Loader for Mac OS X is available. It is available in Enterprise, Professional, Performance, Unlimited, and Developer Editions.

APEX Data Loader is an easy-to-use graphical tool that helps you to import, export, update, and delete Salesforce data.

To download the Mac version, click on Setup->Data Management->Data Loader in your Salesforce Org. Salesforce recommends the uninstall of LexiLoader or any similar tool which you might have been using, before installing the Data loader.

P.S: There is an another useful Data loader tool available which is Dataloader.io and I love it due to ease of use, task history and other features(including scheduled tasks).