Absolutely. The watt limits are determined entirely by surface temperatures; a 40 watt compact fluorescent might give off as much light as a 150 watt incandescent, but won't get any hotter than a 60 watt incandescent.
However .....
The fixture often is made just large enough for a 60 watt bulb to be used, and even a small CFL will have trouble fitting in.
Likewise, the CFL's put out a fair amount of UV, which is what causes the troffer lenses to become yellow and brittle. A CFL in an ordinary fixture will have a similar effect on any plastic.
