Web and WAP
Adding a web server and associated control system to your house provides an easy way of remotely controlling systems and reviewing the current status, whether at work or on holiday. WAP provides similar, if slightly more limited functionality, but using the browser built into many of the newer mobile phones. If you have not yet used WAP over a GPRS connection on your mobile phone, you will be pleasantly surprised - it is very snappy. To be able to use either approach effectively really requires an always-on internet connection, such as ADSL. Some service providers may also impose restrictions on, or limit access to servers hosted on your connection - see *LINK* for more details.
Assuming a permanent internet connection in place, adding web and WAP control is then simply a case of choosing a software package and installing/configuring it. If reliability is a primary concern, I strongly recommend setting aside a dedicated PC for the task. The PC will need to be powered up 24 hours a day, although power saving can be enabled. A typical PC running continuously will add around £10/quarter to your electricity bill.
There are three main contenders for PC based web-enabled controllers: the venerable Homeseer, the open-source Mister House and the new kid on the block, Autom8it. xAP also supports web and WAP access, although it isn't really suitable for novice installation.
Surprisingly resource hungry, Homeseer runs on a Win/32 PC (choose Windows 2000 or Windows XP for reliability), and has a well established support group. There is a general perception that the product is no longer being actively developed now that it has reached maturity. An open API is available allowing end-users to integrate their own devices, however, and this is easy enough to use. My own experiences of Homeseer were middling - I found it a bit of a sloth and not terribly stable. A free 30 day evaluation is available so you can make up your own mind.
Mister House distinguishes itself by being cross platform - it runs under both Linux and Windows, and also includes native xAP support. The Linux configuration is particularly well suited to lower end hardware (perhaps an old, retired PC?). Again, it has an active developer community, most of whom are active "tinkerers". If you have a software background, or enjoy fiddling with technology, Mister House is probably for you.
Autom8it is a new UK based controller in the same vein as Homeseer. Like Homeseer, it is Win/32 based. The product is in the early stages of development, and is currently beta testing. The range of plug-ins is somewhat limited, and the future of the product is a little uncertain. At some point, it is anticipated that it will move from being freeware to a commercial model. Early days, but certainly one to watch.
Update: Autom8it development has now been abandoned, leaving a bunch of disgruntled users in its wake.