Westlaw has just launched RegulationsPlus which, among other things, fills a longstanding gap in the legal researcher's arsenal of tools by providing what amounts to an annotated version of the Code of Federal Regulations (CFR). As described by the West product announcement, "More than 600,000 editorially created Notes of Decisions outline and summarize federal case law interpreting CFR sections. Each note includes links to the case itself, as well as to West’s Topic and Key Number System, to help you find related cases."
Other features of West's enhanced federal regulations database include an online CFR Index newly created by West editors ("more than 1.4 million references, arranged by topic and linked directly to CFR sections"), links to related to code sections ("CFR sections are linked to cited sections and sub-sections of the U.S. Code"), links to prior versions of current CFR sections ("know how a CFR section appeared at a specific point in time"), and access to administrative materials ("While viewing a regulation, link to relevant agency manuals, guidelines, bulletins and other agency content that help you interpret the regulation") and agency decisions ("While viewing a regulation, link to relevant administrative decisions. Covers decisions from more than 150 agencies.).