Some light fixtures state that the max light bulb allowed is 60 watts. Is it permissable to install a 25 watt flourscent lamp that the package says puts out the equivlant of 100 watts? Just something I was wondering.

Since the requirement is based on heat dissipation I think you can assume "watts is watts" and light output is not addressed.

If it is an enclosed fixture, you want to make sure you install a CFL that is rated for use in enclosed fixtures (most Panasonic Lamps)

In enclosed fixtures, there is heat build up which will shorten the life of most CFL's

Thats correct, The heat build up is the killer for most lamps.

Although the CFL runs cooler the end part with the electronics still gets quite hot.
If the heat can't dissipate properly it reduces lamplife and risk of fire.

Check with specs of the CFL lamp.

For incandescent lamps the Watt output is directly related to heat, so if a 100 W lamp is inserted in a 60 W max. fitting, the lamp will have a short life, the wiring will fry behind the fitting and there is an additional fire hazard created.

Regards Ray.