Typblography, an Adobe blog on type, posted Useful Details About Creative Suite 5 (CS5) Fonts. CS5 includes a number of new fonts, and eliminates 3 fonts that were part of the CS4 font set: Bell Gothic Std Black, Bell Gothic Std Bold, and Eccentric Std.
Also, some products in CS5 will install a basic font set while other products will install an additional font sets, some of which have to be manually selected in the installation.
See also last year's article on Adobe Clean.
Update: Sarthak from the Fireworks team takes another approach in Default Fonts and CS5 release.