Daniel Budde pointed out to me a thread over at the Adobe forums that discusses an undocumented (as far as I know) change to GetHTTPRequestData. In the past, if you uploaded a file, the content key of the result of GetHTTPRequestData would contain the binary data of the file uploaded. Adobe made the decision to remove this support as it had a negative impact on server performance when a large file was uploaded. Again, see the thread for more details. Personally it seems like a smart choice by Adobe.