The Sony Tablet S, together with the Tablet P, is expected to receive an official update to Android 4.x Ice Cream Sandwich together with the manufacturer’s 2011 Xperia line of phones. Until then, however, you might be interested in rooting your tablet.
First you need to acknowledge that there’s a risk involved, as usual, when tinkering with your tablet; then make a backup of what’s important just to be on the safe side. Now that you’ve got those out of the way, head over to XDA Developers for the goodies. You’ll be required to put your Tablet S in USB debugging mode, grab the exploit, unzip the archive and run a batch file. For more details (like the possibility of losing your root once an over-the-air update is pushed to your device) and feedback hit up the source link.