api-level

What changes are made in the mass storage API between Android 1.5 and Android 1.6

I wrote some code to save images on the SD Card a while back. Now I added the targetSDKVersion to my manifest and now my file saving code ceased to work. I can reproduce it through removing the targetSdkVersion from my manifest from that on my App won't write anything to the SD Card. Is there an API change between Android 1.5 and 1.6 ...