several arduino-style devices called 'teensyduino'[1] are not shipped
with the arduino typical serial programming, but with their own
bootloader protocol called halfkay[2]. they ship an own command line
client[3], which is not included in debian (i have created a minimal
package at [4], but unless i'm convinced that this tool is the right way
to go, i don't plan on supporting it for inclusion in debian).

the halfkay protocol[2] itself is quite stu^H^Himple -- no reading, no
fuses, no identification, writing only in 128byte blocks.

if it is not too simple for avrdude to support, i'd suggest to include
this protocol in avrdude. (for matters of being too simple, i'd like to
point out that other programmers are only partial as well, for example
the arduino bootloader reports fuses as 0x00 and doesn't accept writes.)
support for halfkay would mean that new teensyduino users could get into
it much faster (using well-known tools).

(for reference, the bug was originally filed in debian as #629360[5])

[1] http://www.pjrc.com/teensy/teensyduino.html
[2] http://www.pjrc.com/teensy/halfkay_protocol.html
[3] http://www.pjrc.com/teensy/loader_cli.html
[4] http://archive.amsuess.com/pool/main/t/teensy-loader-cli/
[5] http://bugs.debian.org/629360