Does this version of Linux support usb FTDI devices (USB to Serial)? I know that Ubuntu on my laptop supports it but will the stock kernel on this device support them.
Like the others here, I didn't let the default kernel last long enough to know this. I'll be receiving another plug in the next two days. I'll test this and report back.
I have heard problems about SD cards dying out very quickly in SheevaPlugs. Is it wise to store important data on SD card?
If this is a major concern, you could use a small (<<100Gig) rotating media attached and powered via USB instead of, or to augment, the SD card. For example, I currently use an 8 Gig SD card (root FS and applications) and a USB attached 32 Gig SSD (music only) to serve all my music via a plug.
The majority of the equation of how long flash (built-in, SD, attached via USB, what ever) will last is how often a particular flash sector goes through the erase/write cycle. If wear leveling algorithms are used in the FS or the device, this concern can be reduced dramatically. Using other methods (aligning partitions on sector boundaries, choosing "smart" cylinder/head/sector and partition size values, etc) can also help a lot.
You say you'll be writing the data to a database. Will this database be on the plug or somewhere else on the network? If it will be somewhere else, the wear on the plug's media could be minimal. If the database is on the plug, are you going to use a "standard" database or one of the ones designed for embedded systems? Most embedded database systems can be optomized for fewer writes to help with flash life.
EDIT: I just tested my FTDI based USB to Serial converter on a "raw" plug and though the drvicr was rcognized (I got new USB stuff in /dev) I don't see a /dev/ttyusbX device. Therefore, I can't say it works with the original kernel and modules.