Hi Bio,
I don't know exactly, but here it goes:
The asus has a specific hardware design.
In order for programs to run on that design, they have to be 'especially' compiled for that hardware design (instructions).
Standard the asus doesn't run any other programs, other than in it's standard firmware (state)
a smart guy named oleg ported the ipkg (itsy package system) to the asus.
(ipkg is a package system which runs 'compiled' software for that specific hardware design. so software has to be specifically compiled for that hardware design, hence, the oleg, stable optware (ipkg) feed)
Now, that said, 'other' linux programs, can be compiled for this system..
So basically yes, you can run linux programs on this router once they have been compiled for the asus..
(and compilation means, giving the package (program) a 'specific' instruction set how to run on/execute on a specific system)
a lot of bla bla... (execuse me.. its almost 4 am.. and I had some beers. )
HTH