I would imagine for this to work decently (OTA OS upgrades) it would need to be embedded in the firmware to download updates (kinda like a network boot on a PC). This means currently devices wouldn't work at all with it. Maybe someday in the future... until then... :(

When I do an upgrade on a 7510, it zaps the phone first and then sits at the 507 screen for a few minutes it seems while the desktop says it is trying to connect to the handheld.

I really can't see an OTA upgrade working in any way without a ton of code. It has to have all the wireless stuff (cdma, gsm or iDEN). It has to locate your BES, sign in with an authorized account over an encrypted connection. Download 6 to 10 megabytes of OS (which would probably take a good 20 or 30 minutes over GPRS depending on cell activity. Flash into the phone all without losing power.

Exactly... which is why I think it would need a major firmware upgrade that has it hardcoded for at least the radio software. If the radio software were always on, at least then you could probably obtain a signal and initiate a download sequence for the rest of the OS.

Still though, this is something I don't see possible with the current model of blackberry, maybe a year down the road or so.. but not now...