Optiboot v2 has been released.
Optiboot now features new serial port code that communicates
accurately at high rates. It uploads at 230400 baud on all 16MHz
devices (all 5V Arduinos), and 115200 baud on 8MHz devices (Lilypad,
and some Pro versions).
Also, all supported Arduino boards have been moved to the new high
speed programming. Arduino Diecimila now runs at 12 times the speed of
the Arduino default bootloader.
Optiboot still fits within 512 bytes, a quarter of the size of the
Arduino default bootloader.
Get the latest Optiboot at
http://optiboot.googlecode.com