Good news!
I have a preliminary driver that supports partitions, the different EPCS chips (ideally) and a read-only filesystem (ROMFS for example). Writing to the chip isn't supported yet, but that will be done shortly... it would help if a couple of people could test this out; I am using a 64Mbit flash, so ideally, other chips would help.
Note: this driver can very easily be ported to any SPI Flash Chip, notably ones made by ST Micro. Very few modifications would be required, so it's not restricted to EPCS.
If anyone is interested, reply to the thread or send a PM.
J