While most people replying to this seem to have gone the way of the Thinkpad T-series, I went with a 15" Edge. They are significantly cheaper than the T and are obviously not as durable, but the keyboard is excellent and I'm very impressed with the engineering on this thing. Removing a single panel from the bottom exposes the RAM, HDD and the Mini-PCI slots. The keyboard is easy to remove and, although it's not got the Ultrabay system, I picked up an aftermarket caddy and swapped the optical drive with the HDD (SATA2 port) and put an SSD in the free bay (SATA3 port). The battery is easy to replace and the screen has a matte finish to it - I'll never buy another laptop without that last part.
On the downside, the screen resolution is not great at 1366x768 and the battery life is mediocre at best - 3-4 hours of light use or 1 hour if I really push the AMD A6-3420 APU hard. Speaking of which, while I may have sprung for the quad-core option at build time, I wish I hadn't - the reduced overall clock rate of a single core when running a single threaded process doesn't hit the speed the dual-core would have managed, even with it's turbo boosting features working flat out.
So, although I have misgivings about this thing, there is one massively important thing that just wipes the floor with almost every other option I looked at - price. It was around a third of the price of other options I considered (Thinkpad T-series and Macbook Pro included) so the fact it's survived two and a half years before the rising threshold of my processor requirements has started to outpace it is highly impressive.