No, I haven't gotten it yet. [Edit] I started a brand new world with 1.5, and have all the other achievements. My rail line is about 1200 meters long, but apparently the 1km achievement measures simple straight line distance from start to finish, not distance along the rail. Oh well. I'll keep building north.
In the meantime, I shot this video hoping to see the "Achievement Get". Anyone else get it?
P.S. Notch, add track sounds like this. Rain sounds awesome, but rails feel funny once you think about how silent they are.
Question, about how far apart on the flat parts were you spacing the power rails? It seemed a nice smooth speed throughout.
On the oldest section (nearest home) it was a little random. Everything else, I started counting and put a power rail on every 32nd meter, with extras near a station. I haven't renovated the station stops with stop buttons, because you need ugly bumps in the track or lots of redstone circuitry that the monorail can't hide. Obviously you don't need vertical posts, but I think it looks better.
Okay, I finally got the achievement last night. New video crunched and uploaded.
Total track length is now about 1700 meters, so that's about 10200 iron and 300 gold ores mined, forged and crafted. Since I paved the whole monorail, and put posts to the sea bottom every 32 meters, I hate to contemplate the amount of cobble I've hauled around.