Do I have to calibrate my battery after a reinstall? When I installed Cyanogen Mod 7, I 'accidently' clicked 'Wipe Battery Status' even though my battery wasn't fully charged.

Now I have no idea what this exactly does (even more reason I shouldn't have clicked it), but I'm wondering whether the phone has anyway of knowing when or if the battery's full.

So should I calibrate my battery and if so, how would I have to do this?
Your battery status may be off for a while, but will return to normal as you use the device.  In general it's good to do several consecutive full discharges and full charges, which will restore the stats about how long the battery lasts.  There's nothing you can do beyond that.