According to Linksys' support page, there is:

We need more details here - info seems very hard to find.

WUSB11v1

Chipset: Prism2 Status: Should work. This is Prism2 as far as I can tell.

According to the KisMAC sources, v1.1 is supported, but this may be the same device...

Identifying Characteristics: None.

WUSB11 v2.1

Chipset: Atmel - will NOT work.

WUSB11v2.5

Chipset: Prism2 Status: Confirmed to work.

Identifying Characteristics: Has internal antenna socket. MMCX type.

WUSB11 v2.6, v2.7 and 2.8

Chipset: Atmel - will NOT work.

v2.6 and higher have no internal antenna socket. Should be fairly simple to mod for one.  Pictures of WUSB11v2.6

WUSB11v3

Chipset: Prism based (Prism3?) - should work.

WUSB11v4

Chipset: Atmel - will NOT work.

WUSB12

Chipset: Prism2 - should work. However, vendor IDs may not be included - anyone have one?