I'm very glad that you liked them, but they are not mine lessons
This is monthly magazine of 3dgamestudio, called AUM, i also had learned by those tutorials and i found them very usefull, so i decided to share links now
If Naughty Alien's algorithm is close to algorithm from tutorials (i think so because of his phrase "calculations are done during grid generation", but i'm not sure), then it doesnt use neither GPU nor CPU during gameplay.
Short summary of those tutorials:
1) first, before game launched a special script runs and creates a large matrix, which consists of paths from each node to each node, this matrix saved to file (it can take some time, but no matter for end user).
2) then, when game started, user just requests "how can i get from node A to node X?" and engine looks into matrix and get only one variable from matrix (this is all work of CPU) and answers "matrix says that you can get from node A to node X through node G, H and L".
Thats all, but, as i said, i'm not sure that Naughty Alien use the same algorithm, but anyway, its very usefull.