I agree with your comments.
Given that TD are selling thousands of these units - heck they've sold out of their initial allocation and have presold 33% of the next batch, then that presumably (@$80 per unit 'cost' to SB) several hundred thousand dollars of moving stock no longer on their books. Let aone what other outlets are selling them too. TD is not the only one - hence these ebay auctions.
Perhaps SB needs the cash, or maybe they need warehouse space for all those HSX109s yet to be shipped, (or even, the next generation Receiver product.)
The HSX 109 does need a device something like this, its odd that the Receiver is being sold off so cheaply now, but then again if you stimulate the market for distributed 'room based' mp3 playback devices, then a portion of these customer will want a central server to put their mp3s on, and that is the HSX-109.
There is also the 'mumble mumble' device that Hugo mentioned at Xmas time when people complained about the large 3.5AMP power brick they got with their firesale Empegs.
[which Hugo indicated is used for a device of some sort - 3.5
amp@12-16V DC is a pretty hefty 'consumer level' power supply].
The RioReceiver is due for a overhaul - there are some design issues with the current design - 4MB of onboard RAM being one of them, small and hard to read display another.
I guess that the car software is being used in another device [like the Receiver] in another guise -SB woudn't fund the v2 release if the software was a dead end - which clearly it is not - even if the guys were working on it in their spare time.