For those interested in reprogramming brushless ESCs based on Silicon Labs processors (many newer HobbyKing/Turnigy/Hobbywing etc) to run brushed motors, check out http://robowars.org/forum/viewtopic.php?t=1581
and the source code (plus a couple of HEX files) at www.launchpad.net/brushed
I just reprogrammed 2x Turnigy Plush 10A ESCs for mini robots. Basically, 1 brushless ESC becomes a brushed ESC with forward/reverse. It's not particularly well documented, and I nearly bricked my first ESC by using the wrong pin definitions file.
I had to download and install the compiler and programming tools (SiLabs IDE and Keil 8051 C compiler demo) and fiddle around a bit, so it's definitely only for folks with some electronics/programming experience. I had previously reflashed some multicopter ESCs with BLHeli firmware so already had some kit set up. I used OlliW's BLHeliTool programming software to do the actual flashing for BLHeli and for this brushed firmware.
EDIT looks like the pages I linked to are the project of SteveQRSC who posted in page 2 of this thread, and also in another ESC programming thread http://www.rcgroups.com/forums/showthread.php?t=766589