Yesterday we heard a rumor that Apple may be experiencing problems with the iPod's new camera feature, and those problems could cause a delay.
Today, Hardmac threw in some rumored details about the rumored problems:
The issue would be linked to the new camera module. We did not get any further details, but the problem has been spotted in the first dozen of thousands units produced. Those units have been put aside.
Again, even if true, this would likely only cause a delay in the release of the third generation iPod touch, not its announcement at tomorrow's "It's only rock and roll, but we like it" special music event. This has happened in the past when products weren't quite ready or had last minute spec changes necessitating a delay.