http://www.zdnet.com/eweek/stories/general/0,11011,2787187,00.html

Excerpts:
Demand for Linux on the mainframe continues to gain momentum, with IBM
notching up another win for its eServer system. This time Korean
Airlines is moving its Flight Schedule Enquiry System and Daily Revenue
Accounting System to Linux on IBM hardware and software.
...
chief information officer at Korean Air. "A single IBM eServer z900
running Linux can do the work of an entire server  farm. Multiple copies
of Linux can run side by side on a server, allowing for highly scalable
and manageable environments that can handle unpredictable spikes in
Internet activity."

I'm not sure, but it sounds like these guys may be running Linux on
"bare iron".

Peace,
Jim