The G1 does have exclusive software on it. And Google is actively defending that exclusive software.

If you consider the N900 to be an N810+phone+updates, then I'd counter that the G1 is, in fact, pretty much in the same category. My G1 does almost everything that I used to do with my N810 ... plus it's a phone. The only things the N810 did, but that the G1 doesn't do (which pretty much boils down to "VNC viewer"), are "nice to haves" not "platform defining features".

(and, there is actually a VNC viewer, I just haven't gotten it to work for me)

The N900 is definitely NOT "in its own exclusive product category" (which is what you seem to be trying to say). There are definitely other devices in that same product space.