Ok, I've got marking on an ATMEGA16L-8AC in the TQFP44 package that I haven't seen before (although I've only owned 4 of them). Three of the chips said ATMEL, then ATMEGA16L below that, then 8AC 0XXX below that. Replace the XXX's with any number, its the batch number I'm pretty sure. The fourth one looks just like that, except that below the 8AC part in the middle of the chip there is a capital "I". The datasheet says nothing about this, and I'm pretty sure it can't mean that it is the industrial rated part, since that should be marked as 8AI. All of my parts are the commercial grade. The chip seems to be DOA, so if it is a different version of the chip (though I've never heard of any), it may explain why it isn't working in my application (desoldering that package is going to be fun... I've already lost one board that way).