Thanks for the link -- I'd just come across: http://www.virtualbox.org/manual/ch11.html
where I saw COM, XPCOM, and other things of potential interest mentioned. This triggered some poking around the VirtualBox site's documentation section, where I noticed the SDK Programming Guide
, but haven't really looked at it in any detail yet.
I'm not sure how nasty taking a snapshot becomes, so some real-world experience via a prototype using easy-to-develop scripts and some scheduling code as you suggested is a path that seems reasonable. FWIW, it looks like the tool on the guest end, vboxcontrol, is headed in the direction of being able to initiate a snapshot. In my locally installed version, I get some message about not implemented yet, so ATM it's looking like a host+guest idea.
On a related note, I started to use Workrave recently and got to thinking that if I was going to be taking breaks so frequently, may be snapshotting could happen during some of those times
This idea seems pretty obvious in retrospect though, so I'm wondering if someone hasn't already done something similar.