Is there a way to enter maintenance/OS recovery modes in the emulator?

No, it's "just" a simulator.

Guidebook, firmware and linking software did leak last week on the HP FTP server and were quickly removed:
http://tiplanet.org/forum/viewtopic.php?f=55&t=12867&lang=en

Come on, it can only have been done on purpose, IMHO!
BTW, has any of you managed to get hold of the "HP-Connectivity Kit"? That would be really interesting. And also the booter code, of course!

Good news, nevertheless!

Which is the Boot Code.
V11 in the leaked firmware.
V13 in the current zip-password-protected firmware.

Thanks for the input.
Here are some thoughts on how i think this hacking business could eventually proceed. Someone ought to write some sort of roadmap. To start with (let's take it easy ), we need to figure out the HP Prime's system:
    architecture surrounding the microcontroller (S3C2416).
    memory map: ROM, RAM, IO, etc.
During this process, some ARM disassembly will certainly be required. This step will be a bit awkward to accomplish here because we'll need to abide by the forum rules, but still feasible by other means.

Please feel free to add your contributions/advice, because i'm sure i won't have enough free time to lead this process.

Yeah, i thought so too, but i am not aware of it. That's nice to hear, though! But don't you think we a need some common place to share that valuable info?

Just make sure to not blatantly explain how to circumvent the teacher mode during exams.

Did the "emulator" come with a reset button on the back?

nah but there is a reset option in the menus. The thing, though, is that even if it actually worked like on the calc, it would be next to impossible to do the key combination and clicking that option simultaneously.