Q:I swapped transistors in CMOS inverter (put n-transistor at the top and p-transistor at the bottom).
Can I use this circuit as a noninverting buffer?

Yuri M, principal device engineer at Nasional Semiconductor :

My opinion is that the output of non-inverting buffer will follow the input level, but I wouldn't recommend this circuit as a noninverting buffer.
Try to analyse the circuit with the input signal slowly rising from GND to VDD. Transistors should switch from open to close state. The conditions for fast switching are worse for transistors of the non-inverting buffer. That means longer time interval when both transistors are open which may result in short circuit and possible damage of the transistors.