Nice ... But I do not think that their got real licenses to use the IP of the machines.
There could be some trouble with the names and trademarks.
In the case of ZX Spectrum it is legal to distribute the files for non commercial use. The MSX system has the custom CBIOS. There should be alternatives for most systems that are not covered by trademarks.
There are official ports of MSX emulator that use the fMSX core, but there are the fees for commercial use. If someone wanted to port some MSX game it is possible to license the fMSX and start to distribute the application very fast ...
Software Houses.
I think that someone was porting games from ZX Spectrum and MSX for use on Mobile Phones, There was some requests for commercial game and Intellectual Properties some years ago ...
How's that N900 working for you? I'm interested in the device since my N95 is like sooooo 2008 and want to update to, for example, the N900 (I love Nokia phones)