According to a newly posted Apple Support document the new 2009 MacBook Pros can use an SD card as a startup volume.
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Can I install Mac OS X on an SD storage device and use it as a startup volume?
Yes. Change the default partition table to GUID using Disk Utility, and format the card to use the Mac OS Extended file format to do so.
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This could be very useful as an emergency boot solution or even give you the ability to run a different operating system from the SD card.
Read More [via HardMac]
-----
Can I install Mac OS X on an SD storage device and use it as a startup volume?
Yes. Change the default partition table to GUID using Disk Utility, and format the card to use the Mac OS Extended file format to do so.
-----
This could be very useful as an emergency boot solution or even give you the ability to run a different operating system from the SD card.
Read More [via HardMac]