According to Anandtech's investigations -- http://www.anandtech.com/show/3794/the-iphone-4-review/2 -- both effects are real. #1 is the one that Apple seem to have screwed up on, and that might be fixable (to some extent at least) by putting something over some or all of the exposed metal of the antenna. #2 is the one that applies to other phones about as much as to the iPhone 4. Both will cause signal loss when you hold the phone, relative to sitting it on a table or whatever.