Macbook and the read only SD Card

Until recently I thought my SD cards from my camera were write protected by the camera formatting.  Apparently it’s just my macbook pro being flaky.  The macbook has some flaw where even when switching off the manual lock switch, SD cards are still readonly.  The solution is to set the switch in the middle between lock and unlocked.  You’ll need to try it a few times to get the position just right, but once you do the card is writable.
Sources:

http://www.jackenhack.com/sd-card-readonly-macbook-pro-card-reader-solved/

https://discussions.apple.com/thread/2166984?start=0&tstart=0