Would an indicator that a 'sync' is happening be good enough?

Not really. It's a minor issue, so feel free to close it WONTFIX... but Android app sync indicators are often just 'this app is stuck trying to sync but it will never finish' indicators. Having the numbers move up in smaller units at shorter intervals would alleviate any user concerns about that being the case.

It takes about 30 seconds to switch from 0 to 500 uploads on my Android 2.3 device. That's long enough that I start to think something has gone wrong... especially if there's a sync indicator.

Still requests things at intervals of 500, but commits them in intervals of 10. I think this strikes a fine balance between minimizing network activity and being responsive.

Fixed in fcd13c9a7195338ec6374cf5ac243ace7a93dd7f

I like the way it works with this fix, but there seems to be something wrong with the upload count.

I had, according to the market version of the app, 2308 uploads. With this new test version, after I uploaded one more, it has said first 2291 and then (after clearing app data and letting it re-read my uploads) 2290 uploads. When I uninstall the version with this fix and re-install the market version, I get 2309 uploads (presumably the correct number, although I can't find a way to verify it).

Closing this bug and opening a new one about upload count.