First, I am a C/C++-Developer, but I also do web-programming. With PHP/HTML/CSS and also with C/C++.
The first thing I am looking for is a high quality keyboard. It should be exchangeable. Even if I am satisfied with my Inspiron 9300 keyboard, it might happen that it got damaged. A laptop with a damaged keyboard is worthless. At next I need a high resolution on a non reflecting display panel. I loved my Inspiron 9300 (on Debian Linux) for it's screen resolution (1920x1200) but unfortunately I had to work in darker edges.
I need to read lines of code. I need overview. I want to buy a 27" 2560x1600 Monitor this year. Dell only offers a 16:9 display. Please stay at 16:10! For coding I also accept 4:3. 1440x1050 is a great resolution for coding on a 12 or 13" display. I would love to see 1680x1050 on a 13" 16:10.
I do 3d programming. If you ask for webdevelopers: There is XML3D which is close to OpenGL/WebGL. I am working on this topic. I don't want to have problems, so I really want nvidia graphics. That's why my Inspiron had the additional GeForce 6800 graphics card. NVidia runs well for OpenGL applications. The laptop had a gread gaming performance - but I am no gamer.
My laptops are usually plugged. So I do not need a big and heavy battery. But I always carrying the power supply which needs additional space in my bag. Please create a laptop with a power supply you can put into the laptop instead the battery. Or half the battery to two identical batteries. So you can select if you need more battery with an external power supply or less battery but power supply is included. To make the laptop cheaper, the main battery could be internal.
I love the trackpad of my Apple Macbook. I usually do not need a button, just tip with 2 or 3 fingers - great!
CPU power is not that neceassary for me. Of couse it cool, but a SSD is more important today.