DHCP - Gotcha, makes sense, that would definitely get pretty messy and fast!

OnBoot helpers - Ah, I see. Is the code for these available anywhere that I could take a look at (either on the Linodes themselves and/or via GitHub or similar) perhaps? I'd definitely be interested in seeing it added [or contributing it myself] especially since it seems like it'd be somewhat straight-forward to add. I'd also be curious if something similar could be added to auto-mount additional disk images that are attached to a Linode at boot time. Obviously the latter concern is pretty small, and is very easily automated around as-is, but seems like another semi-easy addition that would possibly be quite helpful & useful for much of the Linode user base.
API - Yep, that's the route I'm probably going to go down, appreciate the guidance & confirmation. We're already making some similar calls for automated deployment via Capistrano which is configured to dynamically lookup the 'server pool' and deploy the appropriate code / configs to each server in the pool based on its role. Will likely do something similar here as well.

Thanks again for the [super fast] replies on such an old thread, very much appreciated!
FWIW, I'm continually impressed by Linode - basically nothing to complain about - you guys have really surpassed my expectations all around (and my hopes / expectations began quite high)!
Thank you!