Does Gmail support HTML imagemaps?
Short answer: Yes!
I ran a test myself because if you search for email client support of imagemap-clicking, you’ll see everyone pointing to this article from 2007 which sadly reports that Gmail is the only significant email client that does not support HTML imagemaps.
Sometime between then and now (July 2010) Gmail added HTML image mapping support, so those of us who are in the business of designing email newsletters can rejoice and take advantage of this useful oldschool feature.
By the way, if you are an email newsletter designer and you had given up on using background images because of Outlook 2007′s terrible support in this regard, have a look at this interesting workaround.