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Tips and questions relating to the GPS modules from SFE
By gussy
Does anyone know if you can update the firmware on these modules?
By arylin
Yes, you can, for example using gpsflash (part of gpsd project).
The problem is that for some reason firmware binaries aren't
publicly available. SiRF (the company) playing some games, I guess.
By gussy
hrm... i wonder if you can read the firmware back off the device, doubt it.
By arylin
I suppose it's technically possible.

SiRF binary protocol - Flash Update - Message ID 148
"This command allows the user to command the receiver to go into internal boot mode without setting the boot switch. Internal boot mode allows the user to re-flash the embedded code in the receiver."

From what I can see in sirfflash.c in gpsd,
boot mode allows to upload a program (firmware loader in this case),
which can do whatever - take and flash new firmware or
dump existing one.