Ah, but this, this makes it compelling. I know a few people with two TiVos 'cause they record a lot of conflicting TV. With the Series 1, you had to play back shows on the same unit they were recorded on--too bad if you recorded something upstairs and wanted to watch it in the living room. But now, networked Series 2's with the Home Media Option let you watch recordings on any unit by streaming it over the ethernet. (I guarantee you this capacity will be reverse-engineered to play back on PCs.)
If you're thinking about doing this, I highly recommend 100 MBit ethernet. Best-quality video runs at a significant fraction of the 10 Mbps bandwidth, and thus is suceptible to congestion if you've got other stuff going on your house network (or neighbors with 802.11 sharing the RF spectrum.)
I'm not ready to spend money on new TiVos and service packages, but this is enough reason for me to consider it at a later date.