A couple of weeks ago, Gruber posted his take on the possible Apple tablet computer announcement later this month. It's worth reading, but if you want the short explanation as to why tablets are getting buzz again, here's why:

The slate/tablet/pad form-factor packages computation as an appliance rather than as a data-entry terminal.

This is based on an old idea (Dynabook) but the right mix of hardware, software, user experience, and cloud services have never been at a state where a commercially successful implementation of it has been made. The fun thought is that 2010 is the year it all comes together.