I believe...from the conversations here...that some upgrades have been done by Lexus of Seattle, at least one by Bellevue and we Lexus of Tacoma people are awaiting a call indicating that they have figured out how to make it work and we can bring our cars in.
I bought my car from Lexus of Seattle and I got my ECU thingy done the day this forum went down. I think I was one of the first ones on the list. Before I got it done, the service manager put a disclaimer: "With this update, you weill get harsher shifting and there is NO way to go back to the old way." I did not care..I wanted to get rid of the hesitation and that was that. So I got it done, and trust me, it makes a HUGE difference if you drive you car aggresively. I am very pleased. I feel no difference in the shifting..well maybe a bit, but nothing noticable. Just call them up and get on the list. They will call you back when they get the part in. My IS experience just got a whole lot better.
Got the upgrades last Saturday. I notice the improvement most in Power Mode, but it's better in regular mode too. The hesitation I used to have when coming to a rolling stop and suddenly accelerating is..GONE!
Had the work done at Lexus of Tacoma in Fife. Mine was the third car they did. The service manager told me to leave the car in power mode for optimal performance with the upgrades, but I only did that for a couple of days.