The XOOM's currently nonfunctional microSD card slot has likely turned off many a potential buyer, but – if you're willing to take your chances with unofficial software from the Android dev community – the problem has finally been solved.

The solution comes by way of an update to Tiamat, a custom kernel from XDA member bigrushdog. Installation is more or less identical to any other kernel, but if you need instructions, knock yourself out:

1. Reboot into the bootloader by running:
adb reboot bootloader
2. Flash the boot image to your boot partition, then boot back into Android by running:
fastboot flash boot boot.img
fastboot reboot
3. Push the bcm4329.ko, scsi_wait_scan.ko, and any other modules to your /system/lib/modules folder and reboot.
adb remount
adb push bcm4329.ko /system/lib/modules/bcm4329.ko
adb push tun.ko /system/lib/modules/tun.ko
adb push scsi_wait_scan.ko /system/lib/modules/scsi_wait_scan.ko
adb push cifs.ko /system/lib/modules/cifs.ko
adb push vold.fstab /system/etc/vold.fstab
adb reboot

As bigrushdog notes, the contents of the SD card are contained in the "sdcard2" folder (not the "sdcard" repository). Other than that, the procedure seems to be relatively straightforward – if you're interested, hit up the source link to get started.

Source: XDA-Developers via Droid Life