If your parts are analog parts, or have analog and digital sections
(e.g. an A/D), my opinion is that the pwr/gnd connections should be
brought out on pins explicitly. For power nets this is good practice
because then you can explicitly attach the power decoupling/bypass
networks to the pin. For GND, this is good practice because you often
want to attach analog GND pins to an analog GND plane, whereas digital
GND pins often go to a separate digital GND plane.
I have to agree with Stuart. I used to prefer the net attribute method
of hiding the power/ground information ("signal pins" in PADS
PowerLogic), but after dealing with some mixed-voltage systems, IMHO it
causes more trouble than it is worth.