The first thing I can think of that would somewhat fit your description is to partition the drive so that one partition is an HFS+ partition and the other is NTFS. Both of them are viewable only from Mac OSX and Windows, respectively.
I would guess the reason nobody thought of making this for a USB drive is either because USB Flash drives are meant moreso to carry data and not programs, removing the barrier between OS's, and then because it's not too much of a hassle to carry two flash drives of two different colors.
As for burning a hybrid cd to a flash drive, it's very well possible, but your mileage will vary since from a driver level, both Windows and Mac will identify a USB flash drive as a flash drive regardless of the filesystem. You may get a U3 drive (which includes virtually all of Sandisk's drives) with Universal Customizer (alternate link) to put the hybrid iso into the fake CD partition. Only U3 drives have this ability; it's a part of their firmware/drive controller.