What type of radiant heat do you plan on installing? Hydronic or electric? Is it just for the comfort of not having a cold tile floor, or is it the primary source of heat for those rooms?
If it's for actually heating the rooms, and not just to keep the tile floors from feeling cold, then I'd have to disagree with most of what I've seen with regards to replies. I think you should do a little more research on radiant heat, and thermostats for such, before worrying how to integrate the controls with your home automation.
A hydronic radiant heat system either in the slab or a mud job, deals with a very large thermal mass, which initially requires a good amount of heat to reach temperature, but once there ideally it should remain fairly stable. A key element in efficient and comfortable operation is a slab sensor. I saw reference to slab sensors in some other replies, but I think those mentions refer to something that only reports back what its reading as opposed to using it as a controlling factor. A good radiant heat thermostat has both a room temperature sensor and a floor slab sensor. Similar to a typical thermostat, it allows you to set the desired room temperature, but additionally you set slab max and min temps, and these basically act as overrides. If the room temperature is satisfied, but the slab temp is not, it will continue to cycle (important word here, more later) until the slab is at it's min, alternatively, if the room temp is not satisfied, but the slab is at it's max, it will shut off.
Now more on cycling, a good radiant thermostat 'learns' it's environment, and will determine the optimal cycle times (on vs. Off) to maintain the desired temp. Without this, and a slab minimum set, the temperature could vary more than desired. The slab would heat up too much before the room reached the desired temperature and by the time it shut off it would be too late and because of the large thermal mass the temperature would 'creep' higher, on the other end of the spectrum, when the slab, and room start to cool down, by the time the thermostat calls for heat, it's again too late, as the slab ( because of it's large thermal mass) will take more time to warm up before it can actually heat the room, and then the temp drops below that desired.
I have three different manufacturers thermostats, operating various radiant setups (1. heated conc. slab on grade with a laminate flooring, 2. tile on a mud job, 3. tile over a traditional subfloor with aluminum heat track below, 4. carpet over subfloor with aluminum heat track and 5. carpet over subfloor with suspended tubing) and have to give Kudos to TEKMAR, the mfg. of what I consider a superior radiant heat thermostat.
I had been searching for a radiant heat thermostat to integrate with my home automation for quite some time, there's a handful of thermostats out there that can be integrated, but none that I considered suitable for radiant heat due to the lack of a 'functioning' slab sensor. About two weeks ago I discovered that TEKMAR now makes a gateway that links a line of their thermostats with a number of home automation systems via RS232, it looks just like what I've been waiting for, it supports a ridiculous number of thermostats, way more than I need it to, BUT its retail price is in the $1,400 range! Hopefully the price drops significantly over time, and maybe one day I can afford the upgrade.