"One final note -- please don't leave your USB stick inserted in the PC as you power it off! USB ports supply power and use a FET device to control that power. When you turn off the PC, the gates float and significant leakage current goes to the USB device. Some of the cheaper USB drives lack a key resistor that bleads this current away and protects the flash memory chips. This leads to data corruption. I have seen the FTL break in such sticks simply by doing POR on the PC."
With that said, those of us that always leave our SDHD cards in our netbook's card reader, even after powering down: Are we in danger of data loss from a similar manner as described above?
//GO.SYSIN DD *, DOODAH, DOODAH