On August 24th I switched my clock-radio from local radio to internet streaming audio. The experiment has been a roaring success, and two weeks of real-world use has allowed me to refine the system.
Hardware modifications
The initial hardware setup was somewhat jury-rigged as a minimal change to my existing setup. However, this involved the audio input for the transmitter being routed through the hifi amplifer, with the amplifier switched to a particular output. Thus, every night I had to remember to leave the amplifier turned on, and switched in the correct manner. I also had to remember to plug-in the powerpack for the transmitter.
For long-term use, a much better solution would be one involving no user input. As such, I have rerouted the transmitter input directly from the PC, via a splitter which also sends the audio to the amplifer. The net result is that it works with the amplifer turned off, and thus no user interaction is needed.
Linux
I made a half-hearted attempt to get the software side of things working in Mandriva Linux using /proc/acpi and the alarm command, but I quickly got stuck. Whilst it doesn't look as easy as in Windows XP, it does seem that it should be possible. I may try again one day, but not with any urgency.
Audio program choice
It's only after trying to wake up to various programs that you can determine which are soporific and which really grab your attention. I set up a different BBC Radio program each day, and discovered that factual / documentary (though not news) style programs were great at putting me back to sleep. Quizzes and panel games seemed to get me the most alert, with news somewhere in between, perhaps depending on the stories of the day.