gee, integrating writers into the rest of the game developement is a good idea? what a surprise. games will never become a mature narrative artform so long as writers are kept away from the rest of the process. portal was developed by a tiny team and a big part of the reason its such an artistic success is because everyone on the team was at least aware of the the other parts of the game and were thus able to produce a cohesive whole.
the latest prince of persia was relly well written IMO. perhaps a whole post on that at some point