At this point my immediate need for a file uploading interface is to allow web designers to place graphics on a scoop site. Learning to use blocks is not too difficult, so there's a bottleneck when folks need to use scp to upload new images.
This can be easily implemented as an isolated feature, but what other considerations do you have?
One option is to eventually offer a full file hosting and sharing system, like briefcase.yahoo.com. In such a system you can upload into a home directory (and other places with proper permissions) and create, move, copy, and delete files and folders. Also of course files should be viewable and/or saveable to other machines; this raises more permission issues -- who should have access to view or edit your files; also this might lead to offering file format conversions (eg. using TOM server) and other file utilities like machine translation, document comparisons (diff), etc.