Thanks for finding this Jeff ... I was about to post a problem report when uploading files over 1MB with AOLServer 4 :)
Since there is no "unlimited", I would say that a limit of 20MB should be more than reasonable. Why 20MB? Well, it's well over the standard word document sizes that I see but not too large and it's around the max size of raw tiffs that you can get from high-end digital SLR's :)
Just my 2 cents.
