We are actually fully compatible with Safari already; we just haven't yet got round to releasing a little Mac OS app that always runs our JS on mail.google.com.
The downside is that you have to manually start it in your Gmail tab. The upside is that most peoples' Gmail tabs are very long lived and, hey, it works in Safari :)
You can use the following bookmarklet in Safari to get Rapportive: http://rapportive.com/extensions/safari/bookmarklet.js
The downside is that you have to manually start it in your Gmail tab. The upside is that most peoples' Gmail tabs are very long lived and, hey, it works in Safari :)