I did this yesterday, and while all my own commands directly pipe into the OpenGL commands at the moment, I should be able to simply replace functions whenever I need them. So I'll be replacing the matrix functions first of all and see if that works.
Also I've had a few ideas on abstracting vertex/fragment programs, so I might try to implement that this evening, or tomorrow evening.
My GUI system is also starting to be usefull. So I might post some pictures of that soon.
In addition to all of this, I've been contacted by a few people to help up fix their .3ds loaders (after a post I made helping someone else). While my loader now does load some meshes that other loaders I've found on the net don't, I've still got two meshes on my drive that it doesn't load correctly. I'm trying to work those out, and then see if it works. If it does, I'll write a tip/tutorial about it.