I have experienced the same issue when trying to save a wallpaper to my SD card, said something like it wasn't installed. I haven't really looked into it too much yet though.

 

have you tried to reboot your phone? that is a strange one

 

plug the usb to your pc, drag down notification bar, mount the card. then drag down again and unmount, then disconnect from pc, then try

 

you still have the card that came with the phone?

have you ever taken it out?

 

do you by chance still have your card the phone came with?

 

sounds like a faulty card. mount it to your pc and copy everything, try to format it.

 

I am having the same problem with my SD Card. I can clearly see what I have stored there, but my Qik app insists that I need to have an SD card installed before I can use it. (??!!??)

Can you tell me what "BeyondPod" is? It's unclear to me from your post - you removed it? Or you downloaded it from the Market?

 

I had the same problem with "Qik" the video streaming application. It would no longer recognize the SD card after the OTA. All other programs, photo albums etc had no issues.
Mounting/unmounting, physically removing and putting it back in didn't help either, but after I uninstalled/re-installed Qik from the market it worked again like a charm.