Hey Paul, I'm one such person who has gotten around to doing such a thing. It's not so complicated as you think, compact flash card are native IDE devices.
I posted a ton of information about it here: http://www.phoronix.com/forums/showthread.php?t=3424 Including my initial reaction, CF information, information about SSD rewrite capability, and etc.
I also have pics up of my rig, if you wish to see the card "in action".(though it just sits there)
My initial CF/IDE adapter gave me some problems, as it didn't support UDMA. Didn't give me proper performance either. My new one gives me this:
[root@localhost ~]# hdparm -Tt /dev/hda
Timing cached reads: 558 MB in 2.00 seconds = 278.31 MB/sec
Timing buffered disk reads: 110 MB in 3.01 seconds = 36.50 MB/sec
In case you're wondering, I have a Sandisk Extreme IV card. And I'll never go back to a hard drive again, as a boot drive.