Yeah, most of the big cable providers such as Comcast, Time Warner, et al, seriously limit the upload speed. They do this in order to prevent/deter customers from running servers out of their homes. For instance, my cable service with Earthlink gives me a 5,000 Kbps download speed, but only a 384 Kbps upload speed. (Still a heck of a lot faster than dialup, though.)
Most of them offer "business class" packages that you can upgrade to, with faster upload capability, but those packages do cost more than the regular residential packages.
When I have a lot of files to upload, sometimes I'll just go off and do something else... make some coffee, watch a DVD, whatever.