Let me see if I get this right: you are making the claim that the Nokia 2630 has the antenna on the OUTSIDE? That, in fact, the silver-coloured area around the device is, in fact, a metal antenna? No, I see you don't. You claim that you can bridge two internal antennas!
The Nokia user guide for the 2630 confirm that (a) the antenna is INTERNAL, not EXTERNAL, and (b) you should avoid touching it unnecessarily. Specifically, you should avoid holding two fingers up to the top of the backside of the device. This will reduce the signal strength ... as expected.
And that, again, is NOT the problem with the iPhone 4. The PROBLEM is that two different antennas are EXTERNAL, and you can BRIDGE them by holding the phone in what is for many people a normal position.
If you look at the N900 schematics, you'll notice that it has its two antennas in a similar position to the iPhone 4, but *inside*. That, AGAIN, means that if you place a 75kg bag of water between the antenna and the cell tower, you WILL experience signal reduction, but you CAN'T BRIDGE THEM USING YOUR FINGER!
Of course it's expected behaviour. The more stuff - regardless of what the 'stuff' is - the signal has to punch through to reach the antenna, the less signal strength. Why we're not ranting about it? Because it is EXPECTED BEHAVIOUR.
You're not alone in being in the backwoods of Whatever Country. All mobile phones lose signal strength, but only ONE, at the moment, can have the two antennas bloody well short-circuited by holding it. (Short-circuit used imprecisely).
Sheesh. You'd think I murdered your mum or something.