now that we're getting into linux-headers-2.6.x and some of the older 2.4.x can be real pita, it'd be nice if `emerge info` included this bit of information :)
oh, i guess 'best' way would be to find out the version of whatever is providing virtual/os-headers since we cant rely on 'linux-headers' (hppa, ppc, arm, and mips use their own atm)
was added a while ago ...