The quickest and easiest way to demonstrate this is with dev-perl/Apache-Session. We have 1.54 and 1.6 in the tree - 1.6 is truly the higher number (grade school math), but with portage you get: [ebuild U ] dev-perl/Apache-Session-1.54 [1.6] This has horrible implications in the tree, at least in the dev-perl branch.
1.54 *is* later than 1.6.
i ran too fast to open this. probably only affects the perl tree where version numbers are actually mathematically named, not subversions