I like this idea, it seems that rather than calling them 'plugins' you should call em 'modules' which can (possibly) be loaded and unloaded dynamicly (just simple things like Weapons usage, unload one module and load another), so its something like
Game Engine <--> 'Wrapper' <--> Main Bot Dll <--> Modules.
Someone mentioned a few posts back about using 'Hack style hooking', personally, i think this is a great idea. Its just the difficult part would be preventing things like VAC going nuts :p
I used to do a lot of work for the anti-cheat community, so i've read and tested things like the OGC source (Note: I did this locally, and not on public servers. Dont call me a cheat).
Although i dont concider myself an experianced C++ coder (in fact, i'm trying to work out htf classes work properly, other than that, i'm quite proficiant) I've assisted in developing an IRC Daemon called 'InspIRCd' which is coded in C++ and is modular. I'd like to assist in this project in some way, even if i'm just a beta / alpha tester.
Thanks
I'll spend some time reading over Botman's HPBBot source