What is in it for the students?

control over their own learning - encourages them to be independent
allows you to verbally provide a 'spin' on the content whilst the text gives another
encourages multi-tasking, task switching, copy and paste
encourages communication in MANY forms - verbal, E-MAIL, ICQ, IRC
IMHO the non-linear nature models how students want to learn
unlimited access at school, ability to access both text and teacher out of hours
safety-net of print resources if they need it