If you are in need of a phone right now I wouldn't bother waiting and dealing with the constant tech cycle or the headaches of early releases. The phones already out right now will more than meet your needs and have most of the kinks already worked out so no surprises ahead. Any talk of 4G, dual-core, or updates are all just small evolutionary steps that aren't game changers at this point. Don't listen to all the hype and fanboy drivel.
The first thing to look for is size. Go to your local AT&T store or Verizon or even borrow one from a friend. Start with big phones like the EVO or Droid X (both 4.3") and see if they are manageable and if you like the screen size and pocketability. Many people do find 4.3" too big and the sweet spot seems to be 4.0", but others find that the 3.5" of the iPhone is the perfect size, so this you have to find out on your own.
The next thing is to figure out if you can handle a touchscreen keyboard. Since you are coming from a Blackberry, you may or may not care to have a sliding keyboard, which adds to the bulk. There are even Blackberry style Androids, but they have smaller screens to accomodate a portrait keyboard.
Then there is of course pricing. I can guess you are a very practical-minded person with your 5-yr phone so don't settle for anything less than FREE, unless you really want it of course. A lot of current gen high-end phones are cheaply discounted now or frequently have sales. T-mobile, for example, is offering every phone in its entire lineup for free this Feb 11-12 for Valentine's Day, 2yr contract of course. Most people would recommend the G2 (it has a keyboard yay) on that network, or possibly a Samsung Vibrant. There should be plenty of deals for the other networks as well, or you could even go to third party resellers (Costco, Amazon, the kiosk at the mall) which require stricter contracts but undercut the phone prices even further.
Just ignore the Infuse, Inspire, Atrix, Optimus 2x, etc. or all the fancy lingo. Most of the current high-end and many of the midrange phones are comparable right now, so look for what's cheap and what looks good and isn't too big.