it's not true. It's exactly what the press conference yesterday was supposed to make happen.
ALL phones can lose signal when you cover the antenna area and squeeze. The iPhone 4 loses signal when your skin makes contact (as in not the death grip, but just a touch) where the two antennas meet, and that spot just so happens to be where most people touch the phone when holding it. It's poor design, which is why a free case was offered as a bandaid.
Ignore the idjits on youtube. Ignore sensationalist bloggers who only want hits. If you're tech savvy, listen to Ars Technica. If you're not, listen to Consumer Reports. Both have said that they absolutely love the new iPhone, but it certainly does have a bigger issue with signal drop than most other new smartphones.