I know some people have been able to get hibernation (deep sleep) working in OS X 10.5.8. I have not seen anyone definitively state that they are able to successfully hibernate and restore in 10.6.2. I would like to investigate the cause of that problem. From my perspective, there are two components to working hibernation: 1) properly saving the contents of the RAM to the sleepimage file (this is the OS's responsibility) and 2) properly restoring the contents of the sleepimage file to RAM (this is Chameleon's responsibility). We know that Chameleon had some bugs with restoring the sleepimage file (erroneously reporting that sleepimage was too big to fit back into RAM, too old, etc.). I believe those have been mostly fixed (though I am not sure that its method of deciding that sleepimage is too old to restore works correctly or is the best way of deciding whether to restore).
On 10.6.2 (at least on my mini 10v), it appears that the save side of the equation is what is broken. With hibernate enabled, my 10v creates the sleepimage file but does not appear to actually write the contents of RAM to it (yes, I have it set to always hibernate on sleep in the SmartSleep pref pane and disabled secure virtual memory). When I put the 10v to sleep then wake it up a bit later, the "last modified time" of /var/vm/sleepimage has not changed, and an inspection of the file with a hex editor reveals that it is empty (all 00's). This leads me to believe there is some issue (possibly with the dsdt.aml file) that is preventing the OS from saving the RAM contents to the sleepimage file. In turn, this prevents Chameleon from properly restoring sleepimage and produces either the "too old" error or an "invalid signature" message.
So, my preliminary question is, does hibernate work correctly for anyone on 10.6.2? If it works for you, please provide some details about your set up (version of NBI used, any customizations done, any settings you changed in OS X, etc.) Thanks!