Figured some people would be interested, so here's the KIM-1 serial uploader I wrote. It's in vanilla C and should work anywhere there's termios and POSIX (tested on Linux and PowerPC Mac OS X). It supports multiple files at once, encoding them from binary to papertape on the fly, and can optionally start the program immediately after upload. You can also use it with regular preconverted papertape files.
https://github.com/classilla/kimupAnd a couple projects to try that were built using it for testing:
https://github.com/classilla/kimtalkhttps://github.com/classilla/lcdkim