I've got a bluetooth headset and, because the thing wants to get maximum usage out of its single button, it not only answers and hangs-up calls with that button, but if you hold it down for a short period and then release it, it calls the last person you called. And that, my friends, is why people wear them on their ears all day-- if you put them in a pocket, you start dialing people.
Also, when I had a nokia brick phone, it had one function where you could hold down a button and dial an emergency number. I never had an emergency, so I never had to figure out which button that was. However, my phone called emergency twice...when the phone was locked! Guess what? That's a network-enabled feature that cannot be disabled in the phone by a typical user. So now, instead of bothering my friends and family with amusing phonecalls from my pants, it now only ties up an emergency line. Great going, Nokia/Cingular.
(Both of these things tell me to buy the bulkiest case for the phone that I can find, and hang it on my belt like an enginerd whenever possible.)
Also, that quote from Rumsfeld is one of "Rumsfeld's Rules," a pamphlet he's been giving out (and adding to) for about 25 years-- I think my dad has a paper copy and he's been retired since the mid-90s.
Anyway, that quote is from the "Keeping Your Bearings in the White House" section, advice directed to peers working in the executive branch. I'm not sure I'd interpret it too broadly.
Here's the full list at the time of his retirement: http://opinionjournal.com/wsj/?id=85000505
How bad is that when I read Rumsfield, I was thinking Dangerfield? As in, Rodney Dangerfield.
I hear you on the whole key-lock thing. I have avoided that problem with my current (and your ex) phone by keeping it in the cellphone pouch in my manpurse. It's easier to hear the ring from there too, and there is less dirt. But then you are way more pocket-centric than I am.
I think it's a peculiarity of my physiology that keeping things in my pants pockets is always uncomfortable. I have giant thighs, so even "relaxed" or whatever pants are tight around them, add anything bulkier than a thumb drive (including keys) and I get super uncomfortable, especially sitting. So I almost never use pants pockets.
I like apple's keyguard solution in the iPhone (slide finger across). It seems like the most foolproof, while being a very simple gesture. I have very high hopes for the iPhone (of course), because, as you mentioned, nobody with Apple's user/design mojo has tackled the cell phone yet. So far they have all been designed by meth-addicted DeDry drop-outs.
I have my problems with the xv-6700 too, I've lost a second memory card now. It just "popped out" sometime in the last month. It only give you 3 or 4 sounds you can use for reminder alerts, and they are all quiet. Plus, when you get a text for VM, it beeps once and then never again, if you miss that it could be hours before you look at the damn screen and realize. Plus it demands two acknowledgment clicks for every txt message sent out. Plus there is no way to have rings start quiet and get louder. So either I never hear it when I'm in, say, a restaurant, or it's so loud the whole room jumps when it rings at work.