For now you can use multiple DVRs by creating a separate icon or bookmark with ?ip=x.x.x.x at the end of the url.
All other settings are shared between all the icons (shared cookies as noted above). This isn't well tested, but I think it will work.
Works perfectly on 3 different DVRs by specifying the ip in the bookmark as you indicated. One DVR is quite remote (pun intended), in that I am using Wireless G to the router from the Ipod Toch, and Wireless N from the router to the HR20-100 located about 80' away. Very impressive. Nice, very nice work and thanks so much for developing this and incorporating the suggestion to support multiple DVRs.
I was thinking this would also work on a networked HD receiver only, as well. It has an IP address, and since I have WHDVR, I could even tell it to record, and I would be prompted for which DVR to record to. A little convoluted, but it should work on a networked receiver, like my H21-200 as well, don't you think?
HR44-700, WD20EURX 2 TB eSATA/ThermalTake Max 5 Enclosure
HR24-200, WD20EVDS 2 TB eSATA/ThermalTake Dock
HR24-200, H21-200. Samsung UN60C6400 60" LED/LCD
DirecTV since 1995