I'm looking at getting one of the awesome 27" Dell screens that has a native resolution of 2560 x 1440. I've been unable to determine if this resolution is attainable using the HDMI port on the 13" Edge.

I've fail to find anything on Google and can't find any details about supported resolutions in the Intel GMA4500HD spec.

Unfortunately Lenovo tends to hide their detailed specs into large Personal Systems Reference pdfs. Here's the one for Edge machines: http://www.lenovo.com/psref/pdf/slbook.pdf

For the 13" Edge the maximum resolution depends on whether you have an Intel or AMD machine but neither appears to meet your desires. In fact, you may need dual-link DVI to pull that off. But I'm not positive. I have a Dell 2408WFP that I'm very happy with. It's a step down in resolution: "only" 1920x1200. But that's enough to edit 1080P video which the next step down can't handle.

Intel Graphics Media Accelerator 4500MHD (GMA 4500MHD)
Max external resolution: 2048x1536@75Hz

ATI™ Radeon™ HD 3200 graphics
Max external resolution: 2456x1536@60Hz

BTW, seems that things don't improve for the otherwise superior 14" and 15" models.