I found the 320GB WD Scorpio here:
http://www.bestbuy.com/site/olspage.jsp?skuId=8909586&type=product&id=1213047091665
One of the customer reviews says it works great in the Macbook Pro.
Its model number isn't on WD's website or found on Google at all, but there's nothing on the box or site descriptions about the free-fall sensor. WD's site describes model WD3200BJKT with free-fall sensor and no way to buy it, but model WD3200BEKT without free-fall sensor and an option to buy it, in stock.
http://www.wdc.com/en/products/Products.asp?DriveID=477
This might mean that the version with the free-fall sensor isn't the one in stores.
I plan on buying it and installing it into my Macbook Pro 15". I didn't even know about the 2MB cache of the WD Passports! I almost bought one, but decided on this because I eventually narrowed my decision to SimpleTech - Signature Mini 500GB External USB and the 320GB WD Scorpio.
I decided that the 7200RPM and longer battery life was a better benefit than <200GB more and having to do weird things inside of my MBP to make the 12mm (instead of 9.5mm) drive fit.