Toshiba has its ICS update delayed for the Thrive and Thrive 7 tablets. Toshiba announced on its forum that the update had been delayed and the responses were met with disappointment to put it mildly. The delay is most likely been caused by some OS tweaks that the engineers at Toshiba might’ve added. Apparently the changes made to the OS aren’t working out hence the delay in the rolling out of the update.
Source Toshiba Forum