The Governor of Minnesota recently announced that he would like all high school students to take at least one online course while in high school (see
http://minnesota.publicradio.org/display/web/2008/10/23/pawlenty/). He discussed the fact that all colleges are now offering and the tech savvy generation of K-12 students should do the same. However, I think that the average high school student will not do well in this environment. Taking an online course requires one to be very responsible and diligent in keeping up, completing assignments, etc. I am not sure that the average high school student will be very good at this on their own.
I do think that maybe this can work for AP courses or in a highly supervised environment initially. For example, maybe a teacher can meet once a week but have students work independently the other four days. The other thing that I think is most important is for high school teachers to incorporate technology and independent, technology-related activities into their lessons so that students are prepared for online courses in college.