Atmel Flashing Tool from HobbyKing

Hmm, this could open up quite a few possibilities.  It's a device that presses down over an Atmel microcontroller and makes the proper connections to flash new firmware.  No soldering onto pads!  Looks perfect for flashing ESCs.  You'll need the USBasp device as well.

Atmel Atmega Socket Firmware Flashing Tool
USBasp AVR Programming Device
eXtreme Burner AVR software

HK describes it thusly:

This genius tool makes flashing the Atmel Atmega MCU found in many ESCs or other devices using Atmega processors a walk in the park. No need to solder or create cumbersome clip on devices, simply connect the socket flashing tool to a USBasp AVR device and place the socket over the exposed Atmel MCU! 

Requires: USBasp AVR Programming Device for ATMEL proccessors.  Suits the Following MCU: Atmel Atmega8, Atmega48, Atmega88, Atmega168, Atmega328

• Fits Atmel processors that use the "QFP32" package.
• Doesn't fit AtMega64 used in Turnigy 9x.
• Doesn't work for SiLabs processors.

Here's a video where hummingbirdRPV flashes four ESC's without even removing them from his quad.

FTDI and AVR cables

Here's a quick brain dump of the differences between FTDI and AVR programming cables.

• Arduino things use the FTDI adapter.  FTDI is basically a serial/usb converter. 
• FTDI is a company, their main product is a serial/usb chip.
• The Arduino boot loader has code to handle the ftdi loading process.
• Shown is the Solarbotics FTDI basic breakout.

• The KK Board is more hard-core, non-arduino, "pure" atmel.
• AVR programmer is used to "flash" the on-board chip memory, like writing an eprom.
• If you want to take an atmel chip and make it into an arduino chip, you would use an AVR programmer and flash the arduino boot loader.
• Likewise, you use an AVR programmer to flash the kkboard software onto the atmel chip.
• Daddy87 has a great tutorial here.

• "Name brand" AVR programmers are, ironically, more expensive than the HK KKboard .
• But, lots of cheap vendors on ebay, all based on the open-source hardware design of Thomas Fischl:  http://www.fischl.de/usbasp
• This one is from ProtoStack.

Notes on reflashing ESC firmware

A couple of random notes about this.  The firmware mentioned is good for multicopters as it supports a very high update rate.  The code is fast, can support a prop speed of 120,000 RMP... yikes!  On the thread, someone notes "Finally that annoying 8kHz whine from the motors is gone, and motors are very smooth."

• Nice rcgroups HOWTO by Nek.
• Protostack AVR programmer.  cannot use FTDI programmer.
• Using an arduino as an AVR programmer.
• Cheap one on ebay.
• github tgy project. AVR ASM, baby!

Willar ME850 AVR programming system

Micro development system for AVR. (link)

Google translation: "Most mainstream system supports 51 computers and programming AVR microcontroller and experiment, using the whole open-modular design, materials can be used with any microcontroller, very suitable for the majority of colleges, individuals, engineers and technicians to learn and develop 51 / AVR microcontroller needs!"