The Anglo-Norman Dictionary was announced in the late 1940s and began publishing in 1979, the last fascicle coming out in 1994; Glanville Price in his review for The Modern Language Review said it “is likely to have a major impact on our understanding of the lexical history both of French and of English.” Now the whole thing is online; like the OED, they’re updating letters as they go, starting with F. “In December 2006 and September 2007, these were joined by the entries for AND2 letters G and H respectively. AND2 letters I to M will follow during the period 2008-12. These AND2 entries from letter F onwards have not been published in print (nor are there at present any plans to do so) and can be consulted only on this site.” There’s a brief introduction to the language (“Anglo-Norman is the name conventionally given to the variety of French which arrived in England with the Norman conquest in 1066. Possibly it is something of a misnomer…”); the main Introduction has a long and detailed discussion of the history of the language and changing perceptions of it, and describes the impact the availability of the lexical material can have on English lexicography:
In the authoritative dictionaries of English, even in cases where the contribution of French to the lexis of modern English has been recognised, any mention of a French etymology for a word usually refers to the continental variety. The proportion of words said to derive from Anglo-French has up to the present been very small. Now that the new Anglo-Norman Dictionary is becoming not only available, but its contents electronically searchable on-line, many of the current etymologies given in the dictionaries of English will need to be altered to show a derivation from insular French. This is more than merely a change of label: it means that the Anglicist will be able to follow the history of many English words through the French used on both sides of the Channel and note any changes of meaning that came about in the process. It will be possible to show either a semantic continuity or a semantic divergence.
A necessary caveat reminds us of an important difference from the OED:
Readers are nevertheless reminded that AND is not a historical or etymological dictionary. No systematic attempt has been made to supply a chronological account of vocabulary or of semantic developments; an attestation which occupies first place in an entry may well not be the chronologically oldest attestation, which will not always be included at all; and words or meanings may in fact have survived in use later than the quotations in the Dictionary could suggest. The Dictionary’s entries are semantically, not historically structured, and whilst the one might in theory coincide with the other, this will not always be so. Moreover, the range of attestations available to the editors does not of course always allow a complete historical account even had it been our intention to supply it. Caveat lector: absence of evidence is not evidence of absence.
I found this extremely useful resource via Wordorigins.org.