[whpalmer4]

If you look in your Documents folder on MobileMe, there should be a file called OmniFocus.ofocus (possibly just OmniFocus if the extension is hidden). Do a Get Info on that and you'll have the size.

You're certain that the iPhone is connecting via your WiFi link and not a slow cellular data connection? Speed for upload is also important because when the database is compacted, the whole file has to be rewritten. Perhaps you have a symmetrical connection, but most people don't, usually the upload speed is a fraction of the download speed.