Today, Dash 17150 is available on XBLive.
Changes are unknown at this moment, however Xkey and LT users beware.
Updating is at your own risk!
I personally suspect the changes are minor (stability updates as well as XBL updates)
Like the last update, it's said to be an update for the growth of the XBL service.
Source: Meself, just turned on me console.