The PS3 may not be showing fantastic sales right now, but it is showing steady sales. Sony would be foolish to lower the price before the big hits are released, the ones that are going to move more PS3s into consumers' hands. Once they've gotten through the 2007 holiday season and their momentum starts to die down (and the cost of manufacturing becomes ever lower), we'll see a price cut.
Also, if you ever ask Nintendo, Sony, or Microsoft if there are plans for a price cut -- they are always going to say no. Saying "yes" just cannibalizes their sales; who wants to buy one when you know they are planning to cut the price? The most you will ever get out of a PR rep with their head on straight (which, admittedly, Sony's PR hasn't always had) is "We are always evaluating the market to see which factors will result in higher sales, and price is one of those factors." Most likely you won't even get that much.