A friend of mine had a retina-quality screen on his laptop in 2003. I think it was a ThinkPad with a 2048 x 1536 screen. Of course, at the time there wasn't a concept of resolution-independent scaling, so it didn't look as nice as today's retina displays.
edit for context: bsimpson's comment originally said "I think it was a Thinkpad with a 1080p monitor"
Minor niggles:
1. 1080p would have been rare in 2003, considering 16:10 was the usual widescreen format at the time[0].
2. In order for a 1080p to be "retina" (by Apple's standards, not true retina[1]), at the typical 20" viewing distance of a laptop, it would have to be only a 9" screen. I don't think they ever made a 9" Thinkpad, but I could be wrong.
More comparative info on the Retina Display wiki page[2].
Ah nice, that must have cost a pretty penny to get that screen. I still wonder if that's not quite retina though. For better or for worse, Apple coined the phrase, and I'd tend to peg off of that to make 220ppi @ 20" the lower bound for retina-quality. Maybe 200ppi. 170ppi @ 20" is quite a step down from that.
That's 4:3, not even close to the 16:9 aspect ratio that 1080p implies... and you edited your post to take that out. Okay then!
It wasn't my laptop, so I didn't know the details. I just remembered it being around 2000px. My original reply was meant to be a "hey, so I did some research and edited the post." Sorry for any confusion.
Back then almost all UI rendering was software based. The graphics card just needed a large enough frame buffer.
The lack of fancy compositing and animation effects gave these high resolutions devices comparable performance to their standard resolution counterparts.
It was a lot easier back when all you cared about was the 2D performance of basic shapes (lines, circles, fills), and the animation for moving a window was just an outline.
specs: http://www.thinkwiki.org/wiki/Category:R50p