According to:

http://www.onlamp.com/pub/a/bsd/2005/02/24/netbsd.html

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Is anyone working on virtualization extensions to have multiple 
independent systems running at the same time?

...

Hubert Feyrer: On a userland level, work is underway to do something 
like Usermode Linux on steroids: not only are system calls, etc. 
trapped, but also CPU instructions, which allows running non-native 
binaries. An example implementation of NetBSD/arm32 binaries running 
pkgsrc bulk builds on a NetBSD/i386 system was demonstrated at the 
pkgsrcCon in May 2004 in Vienna, and it was very impressive to see the 
system compile packages in near-realtime.
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..it's possibly. Where can i get information about cross-building arm32 
packages on x86?

// wbr