Did you know that OSX has a built-in tftp server? Well it does, here's how you use it:
Type the following in Terminal.app
$ sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist $ sudo launchctl start com.apple.tftpd
Copy the files you want served up via tftp
All files are served out of /private/tftpboot/
$ sudo scp uboot.bin /private/tftpboot/
Happy Hacking.