Capcom has said on its official blog that the West won't get a demo for Resident Evil 5 at the same time as Japan, where the survival-horror sampler will be available on 5 December.
In fact, Resident Evil 5 is so anticipated in Japan, it's actually been pushed forward to 5 March 2009. Unfortunately, it is still set for the original 13 March release over here.
Of course, most PS3 owners will know that regional PSN accounts can be faked so you should be able to get hold of the Resident Evil 5 demo on 5 December. Now that will mean it will all be in Japanese, but if that's the least of your worries, you're set.
If you'd rather wait for the proper release though, we'll keep you updated on any news as to when you can expect it.