toolbar example in http://www.w3.org/TR/wai-aria-practices/

http://www.w3.org/TR/wai-aria-practices/#accessiblewidget (as of July
7, 2009) uses <div role="toolbar"> as an example.

As stated under step 2, subsection (or dt) "supported states and
properties", this role does not have any directly supported states or
properties.   aria-multiselectable would apply to a listbox, but not
to a toolbar.

However, the boxed example immediately following begins with

    <div role="toolbar" multiselectable="false"

which strongly suggests that the multiselectable property is still relevant.

-jJ