There's probably a Parrot book in the future, though that's not certain. (Cool though it might be, there's a limit to the size of the market for internals-level books for most any product) Whether there'll be a mod_parrot book depends on both the existence of a production mod_parrot and demand for a mod_parrot book. Personally I hope so, but we'll see.
Ora's paying Allison, Leo, and I standard royalties (with 20% of the author royalties going to The Perl Foundation, and O'Reilly's matching that) so if past book history in general is any indication, we'll end up getting billed rather than get cash. There's the ineffable sex appeal of being a geek book author to balance that, though. :)
There is, or rather was, a set of articles in Linux Magazine. (And thanks for reminding me--I need to check and see if they paid) The April issue had a Parrot article I wrote and a Perl 6 article that Damian wrote in it.