I think its more possible than a lot of people think. LBP almost needs a $299 PS3 to be successful, we have had multiple hints that the price drops "$100 every year" according to Howard Stringer.
Sony has also cut huge chunks off the PS3 manufacturing cost (it costs half as much as it did in the beginning of 2007.) Since Blu-Ray won the format war, manufacturers are more willing to manufacture blu-ray diodes because of more certainty (less costs there.) Sony has made many hardware revisions, and reached the 65/65 chipset in newer models, and are no longer selling BC versions at a loss. I think it very possibly cost Sony under $300 to manufacture the PS3' core.
Combine this with huge first party games like R2, SOCOM, WKS (Japan) and LBP, followed by InFamous, Killzone2, God of War III next year and Sony will be pulling a fortune off of first party sales.
I think its a gamble, but if they are confident enough in LBP being a hit then I don't see why they wouldn't drop the price to $299. They still have PS2 and PSP sales to cushion any loses, and the huge jump in install base would sit them pretty for the huge first party titles next year, where they could have sales bringing in profits just in time for the fiscal report. Also, this would promote more people to download movies, Qore, etc which already would be bringing in more revenue.
I think PS3 will get SOCOM, Official Headset, Home, LBP, MS2, cross game invites and voicechat AND $100 price drop in October. They'll lose a bit on hardware again, but will make it all back and then some on software. This will be their big hand this fall.
Edit:
This is not to mention that Howard Stringer already stated they make more on software than they lose on hardware.