T-Mobile G1 (Googlephone) and VoIP?

So… what’s the deal? Will anyone come out and definitively say what the fate of VoIP is?

From what I’ve read, there are two distinct issues:

1. The ease of developing VoIP applications on Android, given the lack of a SIP stack.
2. T-Mobile’s shunning of VoIP over their 3G network.

Android - obviously, if we want to see VoIP apps on the G1, Android needs to support SIP. And the best way to do this is with real, native OS support. Even if VoIP possibilities are limited to WiFi, still, it would be nice to have SIP support and let my cell double as a WiFi VoIP phone… even if handoffs between APs are still nearly impossible. The next question that begs to be asked is how well such a third-party app can integrate with the phone. Will the user experience of receiving a VoIP call be substantially similar to that of receiving a normal phone call?

T-Mobile 3G - I’ve read, so far, that T-Mobile “does not support” VoIP over their 3G network. What’s this whole “does not support” thing? I’m still a bit confused about how their 3G network works… do they actively block 3G, or just not enable it? If the latter, doe this mean that other “non-standard” things, such as SSHing to a non-standard port, won’t work? Does this mean that there will be other heavy restrictions on what types of data are sent over the network?

What about tunneling SIP/IAX/whatever else over SSH? Will the G1 be capable of handling that at a relatively good speed?

I’ve read that the G1 “can’t” be tethered. WTF? Firstly, what is this “can’t” thing? Couldn’t a developer just write an app that’s essentially a proxy server, that proxies from some sort of USB-based wired connection to 3G?

Unfortunately, as has been written many times already, less than a week from the G1’s release, it seems that the openness touted by Google and T-Mobile is much less than that. With all their claims of openness, I’d expect a phone that will do anything - especially not be locked to one carrier, given Google’s history of opposing that (their bid for 700Mhz) - and a data plan that would allow anything over the air that my home ISP will allow over the wire.

Google: Have you forsaken all of your stated ideals at the prospect of making some cash off of a phone?