There's been several requests (and hacks) for having the category trail in the breadcrumb trail. Now that categories have a proper edit screen this is potentially much easier. My proposal:

* Add an additional (required?) field to the categories table - short name. (Need to think about what to do to fill the field initially, or perhaps just use the long one if no short)
* Add an option in theme settings to extend the breadcrumb. I would have three options, 'off',' top category only', 'all categories'. Or perhaps just the category depth to display.