Today French site PS3Gen (linked above) have posted what reportedly is a leaked document which appears to confirm both a PS3 Slim model and PS3 price drop this September.
The document is available below and to quote, roughly translated:
"Now Slim or PS3 price drop? Both, Sir!
Several contacts "unofficial" we have confirmed that the two first arrived in September. Slim version is already present in the database under the name "PlayStation 3 SLIM and is posted to 299 €.
No real news for the current version but it seems impossible that his price is not revised downwards otherwise, it would sell more. The Slim is even informally already pre-booked in some shops!
It should be noted that other "offers" PS3 is scheduled for the end of the year after the planning, but it would be, according to our sources, bundles and other offers promotions that are specifically made by this retailer.
This announces Gamescom much spice, and a very nice beginning!"
More PlayStation 3 News...