[Brian]

It sounds like one of the machines you're syncing with hasn't done so in a while. We don't actually remove transactions from the server until all the machines know about them, so if one of the machines has not synced in a while, the transactions build up until they do.

If you press the "Show Clients" button in Sync preferences on one of your Macs, what is the oldest date that appears in the Latest Sync column? If it's more than a week or so, that's what's going on here. Sync the device(s) in question and within a couple of hours, you should see the number of zip files drop.