Amstrad are nice people (tho' if you watch that Apprentice program you probably disagree). Way back when, Amstrad decided to allow the use of the ZX Spectrum ROMs for free. This allows emulator writers to include the ROMs with their downloads (I think there's some restriction on charging money for the ROMs, not sure). But this is just the ROM as software - use of the ROM in hardware is disallowed (ok there's more to it, but for now we'll skip the full legal mumbo-jumbo).
That's where Gasman's latest project comes in. Aowen has been working on something similar for his ZXSE, but I spotted that Gasman has just released an early version of OpenZXRom. The idea is to have a ROM that can be used in newly-developed hardware, which uses none of the copyrighted code, but is mostly compatible with the old ROM.
Currently it's in the very early stages, but you'll be pleased to know that it's already able to play the worlds most annoying game - Manic Miner.