currently piwik is showing the webkit number for safari and not the versionnumber of Safari.
For most webmasters it would be better to see which version (Safari 4, 3 and so on) is used by his visitors.
Requires changes to libs/UserAgentParser.
There's also been requests to split out Webkit browsers into a separate browser family (Webkit), identify the IE layout engine as 'Trident', and similarly, 'Presto' for Opera browsers.