I use blender to create game assets, and these are some things I really think would be useful to cover, as they are useful and not always obvious… Keeping in mind they are all focused on a game pipeline
First things first, how to set up scene defaults, as blender is the only program I’ve ever used that saves preferences and layout in a default file. Setting up some game specific layouts on ctrl+left/right (modeling, uv, animation) would be helpful. Obviously since this is a 2.5 book you should cover some interface customization, like setting up your own buttons in the toolbars and a few examples of modifying the ui scripts.
Modeling stuff, assuming it’s pretty much the same in 2.5:
Quick loop and ring selection, and how to use subdivide and subdivide smooth, edge slide, alt+j, Skin Edge Loops (this one is important, since most people call it bridge and can’t find it), and ctrl click extrude to your advantage. Teaching them how to clone stuff off of the mesh with shift+D on faces and p is very helpful too, as well as joining them back together and remove doubles. Flattening things with S+axis+0. How to use shrink/fatten.
How to get away from manipulators using GRS XYZ and the shift key, and why they should!
Handling multiple UV and vertex color sets, and how to paint vertex colors.
In depth LCSM unwrap/UVs, including live unwrap transform, sync UV and mesh selection mode, angle based vs conformal for mechanical vs organic models, island selection mode, how to assign a UV texture and toggle it (shift+t), how to see and light a GLSL normal map/spec map set up in the viewport, how to set up and preview approximate AO and bake it into a UV texture (I need to do this every day), how to save out the UV layout.
Maybe you could cover getting clean normal maps out of blender as well, as currently I export to maya to do it Not just how to do a normal map, but the tricks to get a good one, and how to swap channels to get it into an engine that uses them differently.
Using the 3D cursor to your advantage. For instance using Alt+D on a column, setting your cursor in the center of a level, and doing R+Z+30 multiple times to make columns perfectly surround something in 30 degree increments. And using Center Cursor to modify pivots, as well as cursor snapping.
Using Automerge editing + vertex snapping to do a Target weld, and remove loop, absolutely essential when you’re doing LODs.
The importance of the modifier stack needs to be nailed, especially Mirror, Subsurf, and EdgeSplit. It’s an odd concept for many people and sometimes they give up on it.
Sorry, I’m sure you already have most of those in mind, but those are what I really needed to know to get along well as a game modeler. I hope some are helpful!