Lenovo has started pushing Ice Cream Sandwich (4.0.3) out to Lenovo Thinkpad Tablets using the Rest Of the World (ROW) and Japanese (JP) image. Implementation seems to be good, and it seems to be stable and faster than Honeycomb. If you have an ROW Tablet and you haven’t got the update yet, you can go to Settings->About Tablet->System Updates. If that fails you can download the image from Lenovo’s download site. Using Rootkeeper you can also keep root if required, though it does involve changing a few files and partitions back to the “standard” configurations before upgrading if you’ve installed CWM.
The US update is set for June 26, “with the possibility of being released earlier or delayed” (nothing like hedging your bets :)), and fixes to the WE and UK images are due June 29.