Owner's of Verizon's LTE-enabled Motorola Xoom should be expecting an update soon, bringing system software to version HLK75F. The update is a tiny 7.8MB, and brings with it compatibility for Pay As You Go LTE service.
Verizon's informational document about the update is tacit on the subject, listing the following benefits:
Now offers month to month, pay as you go 4G LTE Mobile Broadband service.
Updated Google Setup Wizard to improve reliability of Pay As You Go detection on first device power up.
For those interested, Verizon also has a document outlining how to obtain the software update. There's no word on exactly when this update will begin rolling out, but Verizon has attached a reassuring "COMING SOON!" tags to the links leading to the update's documentation on the Xoom's system update page.