The news that Comcast will launch a 100 mbps service in 2008 makes one think. What can one do with that speed in PR ? For one, it would be easy to serve YouTube like videos directly to people by e-mail, for example. This might not work with reporters, but it could certainly appeal to consumers depending on the creativity of the video. It will be easy to transmit high-density photos and art, although computers may not load them quickly on the recipient's end.
The wrong use of such speed, it seems to me, is to dump ever-larger text files into other's machines. Greater speed does not mean more time to read. The temptation to send the whole press kit in a huge Adobe pdf will be more than some PR practitioners can bear. For that reason and to avoid viruses, many news media and other organizations will maintain file size limitations on their networks.
I think it is an huge error to send large, unsolicited, files to anyone under any circumstance. How do you know they have access to high speed Internet? Perhaps they are one the rode and using their phone to check email. Perhaps they are working from home with a slower connection. Simply because you have access to high speed, it does not follow that the recipient does. And that does not even get into the question of whether they are interested in looking at your huge pdf document.