We've run into a little bit of trouble with the low-level serial port code that we're working on. As you know, Mac OS X is based on a UNIX core with some high-level APIs on top of it. But none of the code that we used for Classic GPSy could be used, so we had to build from scratch.
We really are hoping to be able to ship soon. We're just as impatient as the rest of you! And we're really glad we didn't accept any preorders. :-)