The data are available here.
Here is a partial description from the download page:
[…] The United States Code in XML uses the USLM [United States Legislative Markup] Schema. That schema is explained in greater detail in the USLM Schema User Guide. For rendering the XML files, a Stylesheet (CSS) file is provided.
Each update of the United States Code is a “release point”. This page [i.e., http://uscodebeta.house.gov/download/download.shtml] contains links to downloadable files for the most current release point. The available formats are XML, XHTML, and PCC (photocomposition codes, sometimes called GPO locators). Certain limitations currently exist. Although older PDF files (generated through Microcomp) are available on the Annual Historical Archives page, the new PDF files for this page (to be generated through XSL-FO) are not yet available. In addition, the five appendices contained in the United States Code are not yet available in the XML format.
Here are excerts from the press release:
[…]In 2011, Speaker Boehner and Leader Cantor called for the adoption of new electronic data standards to make legislative information more open and accessible. With those standards in place, the House created the Legislative Branch Bulk Data Task Force in 2012 to expedite the process of providing bulk access to legislative information and to increase transparency for the American people. Since then, the Government Printing Office (GPO) has begun providing bulk access to House legislation in XML. The Office of the Clerk makes full sessions of House floor summaries available in bulk as well. The XML version of the U.S. Code will be updated quickly, on an ongoing basis, as new laws are enacted. You can see a full list of open government projects underway in the House at speaker.gov/open […]
For additional selected posts and resources about the release of the U.S. Code in bulk XML, please see the comments to this post.