Thanks for the consideration Mark, and certainly here in China prices for the Atmel 8 M bit parts is no more than 256K "EE" parts, with the bonus of extra speed and built in buffers - so perhaps on a cost basis most users with new designs would also be in the same situation. Also, regarding future file system I also agree that built in support would not need to be for fat or fat32, but it may be worthwhile just documenting how to "port" it into uTasker, perhaps keeping Sourceforge code structure in mind when implementing your "intermediate" file system.
My suggestion woulb be for slightly more complex then the simple implementation (perhaps basic error check of block overwrite, file size would "idiot proof" what you have, and then perhaps even storing an 8.3 filename but not fragmented files or file attributes other then maybe creation date (useful if a data logger app?) since you have an RTC module now.
I have been playing with tweaking SPI flash paramaters and changing conditional assembly to try them both out at once, but not finished yet as I am travelling around a bit at prersent.
One last suggestion a little off topic: - What about a userconfig.h file for all #def options for user customisation so you just refer to one file for most tweaks / user paramaters, and just include it in all the usual source files. then for basic use on one file need be "touched" for basic operation.