Divide Scanned Photos
Scanning multiple photographs with a flatbed scanner typically leads to a big image consisting of the photographs with white space in between. The Image -> Divide Scanned Photos command automatically detects each photograph, rotates it, crops away any white borders, and opens each image in a separate window. The command is equivalent to the The File -> Automate -> Crop and Straighten command in Photoshop CS.
I wonder if VueScan does this? This feature is such a huge time saver it alone may justify purchase of PE 3. Note the Mac version doesn't include the Organizer features; also the Mac version has some serious security issues (won't run well in non-admin account, of course I suspect the XP version has even more severe security issues -- but no-one really runs XP other than in an admin account).