Just an idea, however it would be really nice to see a Sheeva-like box equipped with a Lithium Ion battery. Since this is a lower power ARM device, it should work nicely as a back-up power source. If the plug should loose power, it will still operate using a battery until power is restored. This would make the plug able to process more mission critical tasks in areas not equipped with UPS devices, such as recoding data. It would also allow the user to move the plug to a different location without interrupting services on the plug itself --- if the new electric socket is very close by, then it would result in 0 downtime. If the device was recording offline data, after power is restored and the connection to the server which the data needs to be sent to is back online, the plug would send the data it was capturing.
This type of ability would open the Sheeva plug to far more offline applications. With the USB and SDIO, one could connect a GSM and GPS chip to it, making it easy to track yourself and instantly sending the data somewhere or even accessing it via USB on a laptop or netbook. In the end, there needs to be more user-programmable devices such as this, but go beyond the office or home office. Another idea, would be a portable GSM router, WiFi SDIO, with a GSM USB stick.