I've just finished posting the crunch of Shaman Vurkle in the character sheets thread. As you may know the Spirit Companion is a big part of the Shamans abilities. The things you need to know about Vurkle's mechanics are as follows..
When I heal someone I can give an extra 2d6 hp to someone within 2 squares of the target, not just someone next to my companion.
If you are next to my companion you get +1 to all Non-AC defenses!
Enemies can't move through my companion and moving around it triggers an Opportunity action called Spirit's Shield which lets me heal an ally within 5 squares.
I can attack through my spirit companion, but it cannot attack. A laundry list of what the companion can or can't do is here
I have an encounter power that lets me add 5 to my or an ally's skill check. We should use this all the time!
I think this should be a really fun character to play with.
P.S. Has anyone else used the website http://iplay4e.appspot.com/
? It allows you to upload the Character Builder files to a web interface using a Google login. Then your characters shows up on a nice iPhone interface or a full page one. I used it to copy-paste all of my powers and math to my Mythweaver's sheet.