I think this is a load of crap myself. I bought the iPhone 4 at launch with the bumper. That said, I immediately looked for yellow spots on the screen and tested this reception problem sans bumper. There are no yellow spots, no sparkles, and no reception problems, even when intentionally holding the way described. I am not experiencing any problems. It is a beautiful device, it is VERY VERY fast...the kind of noticeable speed difference there was going from a 386 to a pentium. Also, the screen is so nice. I literally cannot see pixels on it no matter how close I get to it. I can't wait until this is the norm for TV's and monitors...Frankly, the only thing that ticks me off is that my brand new Macbook Pro doesn't have the same screen...mmm, that would be nice.
On a side note, Slashdot has really gotten a tad snooty with this walled garden bullshit. Some people like to sunbathe naked in their walled gardens. Some of us think it's a bit tacky to sunbathe naked in public gardens. Really really good shit happens inside of walled gardens, and you serfs on the outside will always bitch. Noone here likes to point out Apple's open source contributions anymore (Darwin and Webkit), nor do they like to point out that Apple pushes open standards (HTML5, WebDAV, CalDAV, etc). PLUS, Mac is UNIX...real UNIX, and a really good implementation of it at that, yet all I hear on this site is some snooty attitude like Android is better because it's more open...meh, I've got two words for all you haters out there: FaceTime PhoneSex.