Actually, I rather wait on a Firmware hack. The 505 was well supported.
If I think back to the FW updates that came from Sony, the only thing they came up with was the epub thing (obviously not that important for me as I mostly read pdfs). And that was probably only to boost sales of their own online store. All the other things like the dictionary and such was going into new devices instead of supporting allready 6 months old units. Why keep the customer happy with an old device if he can just purchase a new one???