Some interesting things have been happening in home automation communications infrastructure standards. I'll preface this by saying that I'm not an expert, but have been trying to follow developments here for a few years for my own system. I can see four or five different media that you may want to consider. If you don't want to be stuck on an island, the problem to be solved is one of compatibility, especially looking towards the future.
Power Line Communications - these are attractive because your house is already wired for them and the source of power for a device interface is rather obvious. Unfortunately, many solutions are low bit rates, unreliable, or proprietary. Universal Powerline Bus (UPB) seems to be the current raining champion here. Much more reliable than X10, but slow slow slow (240 bits per second). Works for on/off, but won't be useful for higher-end sensor applications. There are other low-speed PLC approaches, some of which are faster (4800 baud even!). What may be the way of the future in PLC is HomePlug AV and HomePlug Green PHY. The former is a high-speed PLC approach (up to 200+ Mbps) that costs a lot per device, the latter is a dumbed-down version of the former that has a much lower bit rate but supposedly costs 75% less in both $$ and power. Its bit rate is still supposedly much higher than UPB. Here the target is something like 250kbps which is touted as necessary for "Smart Grid" applications. IEEE 1901 is a standard that incorporates the HomePlug AV technology; I don't think it includes the HomePlug Green PHY yet, but HomePlug Green PHY is supposed to be compatible (on the same power line media) as HomePlug AV.
Low-voltage bus - here you have to run wires. Ethernet is the reigning champion, running over UTP, coax, fiber (ok - not exactly low voltage but it fits the mood). Great bandwidth, great reliability, but sucks down power and costs $$ for interfaces. PoE makes this useful for remote sensors/controls that don't have a local source of power.
High-speed wireless - you don't have to run communications wires, but the solutions here require more power than you want to supply if running off batteries in a remote location. 802.11 is the champion here.
Low-power wireless - lower bit rates (250kbps) but much less power consumed so that even battery-powered remote devices can be used. ZigBee is one example, which I think is interesting, because...
Ideally you want to be able to tie all of these together so that you don't need to plumb multiple media interfaces into your controller, and ideally you want to be able to use TCP/IP as a high-level protocol. Here is where IEEE 1905 comes into play. The IEEE 1905.1 standard provides an abstraction layer to established powerline, wireless, coaxial cable and Ethernet home networking technologies - IEEE 1901 / HomePlug AV, Wi-Fi, MoCA®, and Ethernet. I think there is some effort underway to get ZigBee into the fold as well.
If vendors see an advantage in following the standard, and interoperability becomes a selling point, perhaps we'll get away from the multiple proprietary islands.