For a physical board with distributed teams, here are some things I done successfully
Have a board buddy
Someone local is a "buddy" for someone distributed. So when the person they buddy with in the distributed team does something, they update the board for them. This has an added bonus that there is more interaction and communication between the team members, especially if you change buddies every week or iteration.
Webcam pointing at the board
The distributed team (and anyone working from home) can see the board status and activity by looking at the webcam feed.
Some ideas I am experimenting with include
Large touch screen devices
Using an online board with a large touch screen device gives a slice of both physical and online board. Using the touch screen you can move cards around the board giving you that psychological experience of interacting directly with the board. At the same time, the board is capturing information about your activities which can be used for feedback and status updates.
With the touch screen, you could also interact with the board in the same way as a physical board, by adding new cards, adding graphical artefacts to the board - such as a "help wanted" icon, updating who is working on which card and most other ways you would interact with a physical board. You could also interact with the scheduling of the cards, by the online board having a slider for priority or T-Shirt size.
As the board is also online, then someone can also update the board using their PC or tablet. This enables anyone to remotely access the board at any time.