The books are available in DRM-free ePub format, which means they can be used on iPads, iPhones, Nooks, and any other device that supports ePub. Books can be downloaded by visiting the Institute's Federal Rules ebooks page from your handheld device and clicking on a link to download directly to your device, or downloading to a computer then transferring to your device.
In related news, be sure to read the latest WisBlawg post which highlights the new Bluebook mobile application, or this InsideTrack article on Mobile apps from the Federal government.