I have been automating my home for some time now, and I hope I can give you some perspective on the process.
Modern (as in, not X10) home automation hardware comes with a steep cost of entry. For my chosen flavor (Insteon), you have to buy $60 worth of phase couplers / wireless receivers and a $80 powerline - computer interface before you can even start adding wall switches. So, unless you are just wildly flush with cash, there usually has to be a need as well as the want to get started.
For me, my house is wired to that the driveway light switch are out in the detached garage. This was very irritating. By replacing the switch in the garage and the switch by the back door of the house with Insteon switches, I can now turn on the driveway lights from within the house. Cheaper than hiring an electrician to re-wire the switches.
Once the initial hurdle is passed, you can do all sorts of things quickly and easily. Such as:
1. I added a wireless switch at knee level so my 2-year old can turn on the light in her room. She LOVES this. A motion sensor turns the light off 15 minutes after she leaves. When she's older I'll set it up so she turns the light off, but I didn't want her flashing the lights on/off/on/off for an hour.
2. The wall switch in the living room can also start/stop music playing, as well as control the volume and change songs.
3. Using some ir-controlled home made window blind controllers I built, the blinds on the first floor of the house are controlled by the computer. Most notably, it shuts them when the sun goes down, so I don't have to worry about people seeing into the house after dark. I got real used to that real fast, let me tell ya.
4. I've put together a "Baby Monitor of the Gods" that sends video (with sound) from an old DV camcorder to any screen in the house (mostly old laptops running Damn Small Linux loaded into RAM, but also either of the TVs). In the workout room the video comes up on the picture-in-picture, so my wife can see the baby sleeping while she exercises. Very popular feature, that.
5. The library did not have a wall switch. Now it does. (It turns on the lamps.)
6. I'm leaving out the basic stuff, such as being able to control a light across the house from the bedroom. Very nice when you are getting ready for bed.
7. Everything is also controllable from our iPhones.
8. Next up is door locks, and after that probably HVAC. Part of me really wants to do computer controlled zoned HVAC, but the other part hates working in the attic. Choices, choices.
All of this runs from a Mac Cube running Indigo. I cannot say enough good things about Indigo, it is one truly great piece of home automation software.
So to sum up, the state of home automation is fantastic. With the relay control modules, you can control just about anything. Add IR control to that and there's not much left beyond your reach. Blind and drapes control is very expensive to buy off the shelf for some reason, but building your own is easy enough.
Good luck (and keep count of how many times you mix up the load and line wires)!
Brian