Universal remote

Has anyone tried to do this yet?

I know there is a company called Savant that has some offering but I don't know what else there is out there and what is the best way to go.

Has anyone tried to do what?

Oh, sorry.
I want to use my iPhone as a universal remote.
e.g. - press a button on it called DVD and it turns on my TV, amplifier, DVD and puts everything on the right channels.

That kind of stuff.

I use a Harmony remote to do exactly that. What you do is set up "tasks" like Watch TV, Listen to Radio, Watch a DVD, etc. Pressing that task's button will turn on all devices used for that task, turn off those not used (if you want it to), adjust to the appropriate input settings for each device, etc. With ONE button press. You can do the same to turn it all off... one button press. This thing is so smart, it actually keeps track of what is supposed to be on and off. As long as it's used properly (and solely... i.e. don't use other remotes to do anything else.. this one CAN do it all anyway), it works awesomely.

I think similar software to get an iPhone to work in a similar manner would be interesting, though already you'd at least need some sort of hardware to get the iPhone to send out IR commands. And unless you plan to leave the iPhone at home, anyone else will be stuck using the entertainment system the hard way.