The nexus one so far looks awesome, as of right now its the most powerfull on the market IIRC, unfortunatly it is on a shit carrier. I was going to wait for the nexus one but i wanted a physical keyboard, and a few things ive seen about the nexus I dont care for. but it is an HTC phone and quality is top notch.
Not counting the nexus one on t-mobile yes, but it wont be for long
A SHIT ton of new android based phones are comming out.
IDK I think webOS could have potential but IMO its way to late in the game. Android OS offers universal search with the search widget on the home screen, as you said type in a persons name/email number etc it comes up and you can go from there. Also while the android doesnt use cards it has the notifications icon up top, press the home screen the application goes away, to bring it back up you can either hold the home screen button and select the app or slide down the notification area and select it.
Android 2.1 has a “card” feature as well and will be comming to the droid shortly, as of now the nexus one is the only one with it.