I've written a Views integration for uc_attributes (it also requires uc_stock). Primary features include:

• Field to show all options for a given attribute
• Field to show all possible attribute option combinations
• Field to show only those attribute option combinations that are in stock (aka above the threshold)
• Filter on the availability of one or more options for a specific attribute (including only those options that are in stock).
• Filter on the availability of a specific combination of product attribute options, with a form that shows options according to the attribute sort hierarchy.
• Argument handler for attribute option availability that allows pass-through of a single option name or multiple option IDs in and/or fashion similar to Taxonomy argument handlers.

Known issues:

• Summary view shows attribute options multiple times
• NOR handling for attribute options filter is not complete

This has turned out to be kind of a tricky contribution to implement, so I'd definitely appreciate help that others can give in the form of testing, code contributions, or suggestions. Hopefully others will find these capabilities to be as useful as I expect them to be for me.

Updated Installation instructions:
Unzip the views_uc_attribute folder into modules/ubercart and go to Admin > Site Building > Modules to Activate the Attribute Views module.