Do you have fink and the OSX developer tools installed? If so, it's easy to build yourself. You need "cmake" and "fltk-aqua" in fink, and gpsd build as described here, then follow the regular build instructions for unix on the obdgpslogger homepage.
Of course, "easy" gets relative, depending on how much of that other stuff you need to do [eg, if you don't have fink and the developer tools, them's a lot of effort].
If not, I'm trying to build a universal binary package right now, which includes making universal versions of the libraries it needs [which I hadn't done before, oops].
Unfortunately, my OSX PPC laptop was sacrificed to make a PPC Linux box, else I'd just build it for you quickly on that :-/
... I don't suppose there's anyone out there who has a ppc mac with the OSX developer tools installed that they'd let me log into remotely to build this stuff, is there?