I'm planning to move the source-code repository from Mercurial to git in the next few days. This change is prompted by slugish performance of Mercurial on some operations I use frequently, such as "hg diff", on the current repository.
If you plan on developing with Gambit, in particular you want "make update" to recompile your Gambit using the most up-to-date patches, then please get ready for the switch by making sure git is installed on your development workstation. Git is available here: http://git.or.cz/ . There are binaries for many OSes including Mac OS X and Windows. It turns out the "hg" and "git" commands have almost the same syntax, so it should be a fairly easy transition for most Mercurial users.
Moreover, up to now Gambit has been released in source form in a single compressed tarball, e.g. gambc-v4_2_9.tgz, which is bloated due to the inclusion of all the revision-control history. In the next release Gambit will be released in 2 tarballs: gambc-v4_2_10.tgz and gambc-v4_2_10-devel.tgz . The "devel" variant which contains the revision-control history should be used by developers. The non-devel variant is about half the size (7 MB instead of 14 MB).
Marc