Keep in mind there are several parts to a Sage system. First you have the tuner(s). You need 1 tuner for every concurrent TV show that you want to record at the same time. There are obviously different types of tuners as well (analog, digital, QAM, ATSC, NTSC, etc) and it is important to match the type of tuner to the type of broadcast source you have.
Secondly, there are playback devices. You need one playback device for each concurrent stream you want to watch at the same time. So yes it is very possible to watch several different things on different TVs at the same time, but it will require multiple playback devices. There are many types of playback devices that work with Sage as well. First and most obvious is the use of a computer. The initial SageTV server license will allow you to watch material via the computer that the server is loaded on to. So you could hook that computer up to a TV and watch it that way, or watch it directly on the computer screen instead. There are also addition SageTV Client licenses you can buy that allow you to watch Sage material on other computers across your network. They run about $30 each and you would need 1 license for each addtional computer you wish to use. Both of these choices require the use of a computer to view the Sage material.
However, Sage also makes hardware based extenders. These are self contained units that you hook up to the network and a display, and they allow you to watch Sage material on that local display (without the need to use a computer to view the material). There are two basic types of extenders - the MVP which is a SD only extender, and the HD-100 and newer HD-200 which are HD extenders (they can also output SD signals if needed). I would recommend looking at the extenders as the playback method because they are much more stable and generally work out of the box. Using a computer to view the Sage material is more problem prone because of all the variables that exist in most people's computer system (ie no two are exactly alike and it may take a lot of tweaking to get everything working correctly - especially the HD material).
Sage also sells a placeshifter license which allows you to stream Saqe material over the internet to be viewed on a computer. This gives you similar function to the Slingbox devices. So if you travel a lot and want to watch you Sage material from the road, you can use the placeshifter to do that. On a side note, the HD extenders also have this ability to connect to a Sage server over the internet, so you could also travel with the HD extender and do the same thing. The advantange to that is it doesn't require an additional license to work.
