I can offer a few tidbits that I gleaned from a conversation with Carl at this year's JagFest, but I won't reveal enough to give away any surprises. I expect that he'll have a press release handy when the time is right.
1) Phase Zero: Carl does not yet have source code, but it appears that code was NOT discarded (as was previously speculated) and that when (hopefully not "if") it is found, Carl will get it via an agreement with the former Hyper Image folks. In a best case scenario, it may still be a few years before a more-complete PZ is released. In the meantime, due to Carl's rights granted by Hyper Image, the B&C carts are now carry the Songbird label. Some cart transfers from B&C to Songbird are supposedly part of it, too.
2) "Mystery Jaguar Projects." PZ is not one of the projects to which the Songbird site alludes. Here are some hints towards the identity of one of them: Protector:SE's JagFree CD routine is there for a reason... and Carl has access to more than just unpublished Jag games...
As for the second mystery project, I really don't have a good guess. It could be another hardware/accessory item, a licensed game, something original, or a game being published for another homebrew developer.
3) "Mystery Lynx Projects." Carl told me about one upgraded cart that will _probably_ be in the works, but I don't think that he was counting it as one of the Lynx mysteries.
-Eric (hoping for news at CGE)