SWIFI is an example of a “fakeblanked serial payload”. It examines your wifi calibration tables and corrects them if necessary. It doesn't require a baseband erase and is very quick, but it requires you to be fakeblanked. The BootNeuter application (part of the pwnage release by the Dev Team) lets you quickly go back and forth between fakeblanked and normal.
The fixer will be incorporated into PwnageTool asap; however, if you just can't wait it has been released for your convenience.
CAUTION! This fixer should not be used unless you have the grey wifi problem described above!