Since AI10 files can't be opened by some software, we ask that contributors include the file version in their descriptions. If you're uploading AI8 or lower there's no need to include the additional note
Some other information that clients request a lot are what effects were used (meshes, blends, clipping masks), whether shapes are grouped, if the file is built in layers, the color space used (RGB/CMYK), etc. It's always a good idea to include as much information about how the file was built!