I don't have an Android, but my girlfriend said she needed an SD card, so I got her one. She put it in her phone, it just said 'setting up SD card' and she didn't have to do anything else.
It made her ringtones for specific callers stop working. Then it stopped even showing her downloaded ringtones in Zedge and started using a 'default' ringtone which is one she had never heard, her phone is a T-Mobile Touch and its default ringtone is the T-Mobile theme, not the one that is playing.
She has also been using a pet shop game on her phone for about 2 years and now she can't use it. It will just say the app isn't installed. Going into the application manager, I can see that there is a file with the word 'petshop' in it saying it is on the SD card, the file and the other 2 (one is eBay app) are grayed out.
The whole purpose of the SD card was so that she could move all of her pictures of our son onto it in order to have them printed out or to move them to a new phone when she gets one. I don't honestly even know how to do that.