I tried it on my Omnia 2 and N900, and signal loss did not happened.
Maybe, because am out of the US and I am a customer of T-Mobile Hungary that has the best 3G/HSDPA service all over the world.

So Apple sucks (only in the USA?), cause I tested the iPhone 4 over T-Mobile Hungary, and it did happened, lost (only) 2 signal bars immediately when I hold the phone like on this movie. But I don't care, cause iPhone 4 performs better on networks that outside of the USA!

So, this signal loss only happens in the USA, poor mobile network development, poor Apple development.

Apple sucks, but iPhone 4 still rocks and will forever, cause Nokia cant produce any stylish product, ever!