2006.09.28 15:05 "Re: [Tiff] Is libtiff Handles EXIF IFD??", by Phil Harvey
In this post, Andrey mentions that a full-featured release including documentation well be issued "really shortly". This was 9 months ago... any word on the progress.
Also, he mentions this is "read-only" support, but I think Anurag want to write this IFD as well. Can that be done?