The project employs the service of File, FormData, and XHR2 objects and avoids popular JS libraries (for now). It turns out Firefox and Chrome have both supported the File and FormData APIs for at least a year, but IE 9 (ha!) and to my surprise Safari 5 do not. Telling my Safari users to download WebKit nightlies is pretty lame. Worse, if I cared about IE users I’d have to point them to IE10, which at the time of writing is only publicly available on Windows 8.
For a company in such a hurry to see Flash die, Apple is keeping Safari in a weird limbo right now. It got slower with Lion (I’m not alone noticing this) and despite a history of innovation is lagging FF and Chrome’s JS support. (I eagerly await the day IE counts as competition again.)
Safari 6, get here already. My project is awesome and wants you, yes you!