It would be nice if FogBugz could get rid of the antiquated form field upload for case attachments and use a Flash file uploader to provide a progress bar. It's also possible to completely get around the max HTTP request size using Flash.
Of course if Flash is not installed or is blocked, it should degrade gracefully to the old uploader.
This also has the advantage that the files can begin uploading before the case is submitted, while the user is still typing out the case (if they choose to attach the files first). This can save a lot of time.
I'm not familiar with the Gmail uploader (probably the only person on the planet!) but in case helpful: looking at that link it is similar to what Wordpress use (and possibly is used by YouTube too), from this open source offering:
You don't need Flash. You can do it with CSS and JS, both the progress bar and the click-to-open Open File dialog box. Right now it takes two clicks to attach a file. We have this in our own internal website, so I know it can be done ;)