Few things to consider ...
- a syntax that does not cause a higher version to be interpreted as a lower one (happened in case of Opera); e.g.: 1.01 != ( 1.1 = 1.10 ) & 1.01 < ( 1.1 = 1.10 );
- a syntax which would allow easy sorting outside of perl software.
BTW, what is the problem with using ISO 8601 dates as version number?