There's a bunch of different solutions. One of the more feature rich and professional is HAI (as well as being an established company). It'll do security, fire, HVAC and lighting. There are both internet and telephone control extensions. Not exactly cheap.
Also, you might just want to run through a site like Worthington Distribution for a good spectrum of automation products. www.worthdist.com
I don't know alot about the consumer/DIYsolutions, but I know enough about the pro stuff. I do installer tech support for a company that makes touchscreen controls that integrate with HVAC, multi zone music, media servers, internet, home theater, security, drapes and blinds, cameras, intercoms, etc, etc, etc....everything nobody really needs, but it's cool to show off at a dinner party.
I'll answer whatever questions you have or ask others around here and we probably have contacts with installation companies in your area.