Speaking with our local GAME store's manager today, we've learned that a similar deal is a "possibility" regarding the PS3 Slim.
"The announcement was only yesterday," said our local GAME store manager of the Slim, "It's a little too early to say at the moment. However, it's certainly a possibility. We'll find out within the coming couple of weeks."</blockquote>
40GB Playstation 3s currently receive around £150s of store credit when traded in at the store so it will be interesting to see whether GAME launch a promotion similar to the DSi, giving those who trade-up to the PS3 Slim a slightly better deal.
We'd happily cough up £80 or so to upgrade our office 40GBs up to fancy Slims.