The first session I attended at SLA was one given by Stacey Greenwell from the University of Kentucky on "Applying the Information Commons Concept." Some of her tips about things they did in designing their commons for undergraduates that were successful include:
Furniture: Put everything you can on wheels. Buy many more whiteboards than you think you need - students love them. The Hub has 20 but could use another 20 more. Do not use TV monitors for signage. They are not as easy to program as simple projectors.
Services:They have replaced their reference desk sign with one that says "Help * Help * Help. They have a mobile reference desk too but are still looking for ways to increase reference traffic. They now offer workshops in RSS and SecondLife. They are partnering with their IT department to offer a laptop clinic. They have a tutoring kiosk (through a video conference/chat system) that allows students to get help from the writing center while in the library. They are going to set up a kiosk in the IT labs for students to get help from librarians. They have trained students to be "navigation assistants."
A description and pictures of The Hub are on their website along with links to more pictures on Flickr.