I think he bought an AI-S version of the 50, NSX. It actually makes some sense because the 50 1.8D won't focus on the D5000 anyway. I still wouldn't have recommended it over the AF (D) version because you've then got metering on top of manual focus to worry about, but I'm glad you've liked it, Danny.
If you really like that focal length, you could save up for the 50 1.4 AF-S. Or, you could also sell your D5000 to get a D90 and a 50 1.8D. The price difference between the 1.8 and 1.4 (~$300) could almost cover the difference in price from selling your D5000 (~$400) and getting a new D90 (~$775). If you like using an AI-S lens on the D5000, I have a feeling that you would fall in love with having two command dials and shooting manual. For me, it's the perfect balance between auto metering (the meter still tells you if it thinks you're underexposing/overexposing) and creative control once you get smarter than your camera. And the LCD screen on the D90/D300s/etc. is a thing of beauty.