Uhm SATA != ATA.
ATA or PATA OR IDE stands for Parallel ATA:http://en.wikipedia.org/wiki/Parallel_ATA
They are not compatible. Namely because SATA has 2 differential data lines, transmit and receive where as PATA( or ATA or IDE) has a 16bit wide bi-directional data bus. In addition SATA is rated at 1Gigabit/sec, 3Gigabit/sec and soon 6Gigabit/sec while ATA goes from 16Megabit/sec up to 133Megabit/sec.
Now Compact Flash is awesome in that it essentially uses a cutdown version of the ATA standard, so in theory, wire up a full 40pin connector and any ATA/IDE 1.8"/2.5" or even 3.5" desktop hard drive would work. However you would need to supply a fair amount of electricity to power a 3.5" 500Gigabit HDD on both the 5V and 12V rails.
One thing I've been really really interested in is an SDHC card based MP3 player. An upgraded waveshield essentially, especially when you think SDHC goes up to 32Gb, and SDXC goes even higher.
Anyway, just some ideas/notes. Sorry for the thread necromancy.