The good news is that Jackflash for OS5 will be released very shortly (next week?) - I'm not sure if it's in its final form or if it will be a public beta... The NX70v should have over 4 megs of available flash memory that can be used by Jackflash.
The bad news is that Brayder now believes that an OS5 version of Jacksprat for the Clies may not be possible due to limitations in the OS. They are still investigating whether they can get around these limitations, but Brayder's current word is that it just may not be possible.