Advanced non-debug install: alternatively, for advanced users that build illumos without debugging, you can install with onu for non-debug builds (without  'F' and 'D' characters in NIGHTLY_OPTIONS variable in illumos.sh). 

Note if you create both debug and non-debug builds you need to be very careful as you will not get a "missing directory" warning if you build with the wrong set of packages:

$ sudo ./usr/src/tools/scripts/onu \
    -t nightly-`date +%Y-%m-%d` -d $PWD/packages/i386/nightly-nd

You can now reboot into the newly generated build, and you will then be running illumos!

$ sudo init 6

For more information about onu, see the man page:

http://illumos.org/man/onu