Game consoles are sold at cost and the manufacturer makes their profit on the sale of games, which have a large profit margin. The reason Sony limited the production of consoles is to manage their cash flow, they don't make any money on them. Soon some Linux hackers will install Linux on these consoles because it's a cheap way to buy a high powered computer for a fraction of the cost of a similar PC.
Actually, for $600, you could get a better PC than the PS3. It wouldn't have the same graphics capabilities, but only having 256mb of RAM pretty much disqualifies the PS3 from being a "high-powered computer" right out of the box.
Consoles don't have the same kind of raw power as PCs; they get away with it because software can be so highly optimized for such a specific platform, and because most of the issues that come with a general computing operating systems aren't present. There are already CPUs and GPUs on the market that far outdo the PS3's.
(And Sony and Microsoft actually LOSE money on every console sold)