Not the design update that has happened over last month or so. There seems to have been a Google Image Search index update this weekend.
A DigitalPoint Forum thread has discussion:
Anyone notice some large changes in the amount of traffic they are recieving from google images? Mine was cut in half overnight. Its not really high conversion traffic, but I am still wondering.
Yup noticed a drop as well.....around 75% drop for me...not that it matters..image traffic is pretty worthless for me.
There is also an updated thread at WebmasterWorld with this comment:
Well, we were knocked from 4000+ original photos to about 167 in July. That's crawled up to 327 in the last few weeks.