Central...
"I'm talking about the USB CF reader -- that's the same thing as the Jumpshot USB cable, right?"
No. Entirely different critters.
"I can't imagine a manufacturer not making a CF card USB compatible!"
Getting really confused here. Every CF card I'm aware of is "USB compatible" when you either: 1) hook your camera to a PC via a USB cable; 2) put your CF card into a USB reader (e.g., Sandisk's); or, 3) plug your CF into a "jumpshot" cable. (Some cameras also offer a s-l-o-w serial-port hookup to read CF cards.)
But not every CF card is "USB enabled" -- Lexar's term to describe it's proprietary CF cards.
If you've found that Lexar's JumpShot cable works with other vendors' CF cards, something significant has happened in the CF market -- other vendors have jumped on (licensed) Lexar's "USB enabled" technology, eliminating the need for CF readers.
Here's a link to Buy.Com's Sandisk CF reader. Is this what you're using? Or are you using something that looks fundamentally different?
Sandisk CF Reader at Buy.Com
Here's the description of the product originally posted:
"Use your Lexar USB enabled [CF] cards with the JumpShot cable to [download] photos to your PC.... You don't need a reader with Lexar only!!"
Note "Lexar USB enabled" and "Lexar only!!". Enlighten please.