Writing for Electronic Media

How has writing for electronic media changed in the last 25 years? I'm anxious to hear others' thoughts on this subject so that I can pass them along to my students. The most obvious change is the need to write for the web, especially for historically print-based media. Does this mean writing for television has changed less? It seems logical, but I'd rather hear from practitioners.

I'll be adding links of interest to my students, and I will be delighted to hear from anyone who has information about great scriptwriting sites.