There has been a recent update to the WebWorks SDK from RIM to help fix a small sandboxing logic issue that was pointed out by some devs after the previous release. This latest update fixes these issues and also gives a clue that points towards SD cards being supported in BlackBerry 10 devices.
The latest trend in high smartphones is a move away from SD card support, and since we did not see it in the PlayBook or in the BlackBerry 10 Dev Alpha many had assumed that the official BlackBerry 10 devices would not either. A new API in the latest WebWorks SDK allows developers to query for the static readonly full path on the SD card folder. This is not a function of BlackBerry 7 that has been brought forward, rather it is a completely new API and process that will be unique to BlackBerry 10.
I am sure that many BlackBerry users will be happy to see SD card support on BlackBerry 10, and hopefully we will finally able to access the memory they provide better than we have on previous BlackBerry devices.