I'm not sure I understand the need to organize new innovations into "generations". I see the current tablet offerings as a solution to a different problem than the one PCs currently solve.

The idea that tablets are "post-pc" seems far too limiting, and I think it reflects the current trend in consumer electronics to race for some lowest-common-denominator-does-it-all-general-purpose device, rather than understanding that different needs can sometimes be better solved with different devices.