atm, when you see a new -r version for a package, you have to go to /usr/portage/<pkg dir>/<pkg name> and less the changelog, which imho is a bit long winded. Adding a --changelog option to emerge would automatically less the appropriate pkg changelog file so you can immediately find out if it is worth recompiling to get the extra features the newer -r version has
*** This bug has been marked as a duplicate of 6124 ***