From a recent speech by WTO DG Pascal Lamy:
Trade, or more specifically financial services liberalization, was neither a villain nor a cause of this crisis but a casualty. As you all know, in the world of the GATS, “liberalization” is essentially about opening specified sectors to competition on a non-discriminatory basis. It does not mean deregulation.
It may be true that "liberalization" is not the equivalent of "deregulation". But isn't it the case that deregulation (of some sort, to some extent) is a good way, and sometimes the only way, to open up competition in certain services sectors?
ADDED: Let me just add that generally speaking, I don't think the GATS requires deregulation (although there may be instances where it encourages it). However, there are a number of areas, including financial services, where the scope of the restrictions placed by the GATS on domestic services regulation is a bit unclear. This lack of clarity can be a problem in a number of ways, especially in the current financial crisis.
