I have similar concerns. Local township inspectors are requirind a receptacle be installed in bath & powder rooms if one doesn't already exist, in order to sell a home. They allow, however to tie into the existing light fixture, that often has a receptacle mounted in it(this must be disconnected). The reasoning is that you are not really adding any additional load, and if it didn't trip before, it won't now. This is not ideal, but on a slab-built home with no overhead access, it would cost hundreds of dollars to run a new circuit versus around $100 to tie in to the fixture and install a GFCI receptacle. The bottom line is that the local AHJ has final say.
[This message has been edited by Redsy (edited 07-17-2001).]