microSD is pretty amazingly small!
This could prove to be useful for our zaurii, maybe even for internal modding or something.
Yes, it might be possible. It's much smaller than all USB devices I tested.
But there are some problems:
Zaurus slot uses metal shield for the SD card. I would expect pretty bad signal.
When you embed this card internally to the SD/SDIO slot, you will lose SD capability. Yes it is possible to build SDIO multiplexer, but it is not a trivial task.
You can attach such card to the SPI bus. But you need to check twice, that both driver and card support SPI mode.
Module like Wi2Wi W2CBW003 may be a better solution for embedding. It's smaller (well, using external antenna) and it supports Bluetooth as well. You will have to solve the same problem (SPI or SDIO?), but you have to sign a NDA.