When I was at my office I was able to sucessfully upload to my Dockstar using the Firefox 4.0 RC1 (which will be released as Firefox 4.0 next week).

When I got home, it didn't work.  It would just sit there and never upload when I dragged a file into the window.  I got no errors, it just didn't work.  I clicked cancel and ended up with a 0 byte file with the name on my Dockstar.   I tried Google Chrome with the same result.  I also tried Apple Safari, but that wouldn't even allow me to drop in the box (there was a circle with a line through it).  I even tried disabling my firewall software (Norton Internet Security), but that made no difference.

So basically I couldn't get any browser to work locally.

On a whim, I tried enabling the option to "use full security sessions", which basically forces all connections to be non-local.  After doing that uploads worked without an issue.

So for whatever reason, uploading using HTML5 won't work when I'm local.