There's talk about some of the big changes in Plone 3, but lots of little things that were changed in the UI as well.
In Plone 2 there was drag and drop re-ordering on the folder contents page. That was implemented by clicking and holding on the item. To access the item you just clicked. That was the theory but in at least one release of Plone IE had a real problem with this, meaning the click to access the item didn't work. Plone 3 makes this much more obvious by clearly seperating out the click to access from the drag to order. The latter is now those 2 colon's on the right.