I hacked together a Kendo plugin that uses the drop down UI (and associated styling), does multi select using checkboxes, and is bindable against a Kendo MVVM view model. A multiselect drop-down is a huge gap in the Kendo Web toolkit, so I figured it might be useful to others as well.
Fiddle is here:
http://jsfiddle.net/bDvkQ/
The reason for using check boxes is so that the user may select many items in one pass. The default behavior of other types of multi-select drop-downs (e.g. Chosen) requires 2*n clicks for n selections; one click to open the drop down, and a second click to make a selection, then the popup closes again. This is fine for infrequently used forms, but when the user hits the same form dozens of times a day, minimizing user clicks is important. This drop-down requires n+2 clicks for n selections.
This could benefit from Select All and Clear actions as well, but I ran out of time. Feel free to hack on this further to suit your needs. As-is, no warranties, and all that.
Kasey