I'm glad I read this thread, I thought I was going mad thinking I could smell the Lexus air-con.
Funny thing is, my car is parked at the back of my work all day near a load of air-con units on the building, I assumed it might of been those!
I'm sure my air con didn't smell as described above last summer (when it was 6 months old), I notice it more on a hot day and switch it on max (which recirculates internal air) after my car has been standing for a few hours.
I'm gonna mention it to my dealer (where my IS200 resides right now getting 5 new free replacement wheels to replace the corroded ones!).
Will post comments here (if any!)