By now you've probably heard that Apple (Nasdaq: AAPL) is addressing the outcry over the "death grip" signal-strength loss in its iPhone 4 by offering free cases for all buyers. But there's something much more important going on here: Somebody is lying.

During Friday's press conference, CEO Steve Jobs played a video showing the effects of left-handed grips on various other smartphones based on operating systems from Google's (Nasdaq: GOOG) Android, Research In Motion (Nasdaq: RIMM), and Microsoft's (Nasdaq: MSFT) Windows Mobile. In each case the signal strength dropped four or five bars, and then returned to full strength when released -- nearly identical to what happens with the iPhone 4.

Over the weekend, the phone makers fired back. Samsung, HTC, RIM, Motorola (NYSE: MOT), and Nokia (NYSE: NOK) all released statements more or less denying what the video showed.

So, somebody's lying: Apple, or everyone else. Together, we can find out.

Here's how you can help. We'd like to know what happens with your smartphone. Please view the Apple video here (the demonstration begins at the 6:30 mark). Note how the phones are being gripped, and try to replicate that grip on your device. Let us know what happens in the comments box below.

For example, my report is below -- it would be helpful if you use the same format.

Model: First-generation iPhone
Carrier: AT&T
Before/after death grip: 5 bars before, 5 bars after (no change)

Hopefully, we can get to the bottom of this. I'll compile the data and report back with another story in the next couple of days.