Microsoft has clarified battery care at the support site:I plan on getting a docking station at some point and I to will probably leave in the dock for long periods of time. I think this is something MS should clarify as to whether. It's a good or bad idea, after all they are making the docking stations.
http://www.microsoft.com/surface/en-us/support/hardware-and-drivers/battery-and-power-pro
In nutshell.... at least once a month run the battery down below 10%....