I haven't gotten to play around w/ .11g, but when I helped set up the WAPs at the UofMn, Twin Cities campus, we used the non-.11g version of
these. They are kind of pricey (being primarily business systems) but they work through four feet of concrete walls in the buildings where I did checking.
You also have the option to buy a .11b compatible device that can be upgraded to .11g or .11i when it comes out (though you'll probably have to pay more for it).