Looking at the Nant and Nantcontrib repositories at Sourceforge I noticed that the last release of Nant is from December 7th 2007 and the latest release of Nantcontrib is from October 15th 2006!
So, is it looks like the development of these tools has stalled for a while. Is anyone still working on those tools?
Is it smart to invest my time into getting proficient on Nant, or should I just invest the time into MSBUILD?
We stopped using NAnt once we moved to .NET 2.0. MSBUILD functions much the same way and allows you to easily integrate with continuing integration servers like CruiseControl.
I'd spend your time on MSBUILD.
Also see this: http://stackoverflow.com/questions/1300/is-nant-still-supported-and-suitable-for-net-35vs2008
See the official blog - NAnt’s not dead, it was just resting
https://sourceforge.net/apps/wordpress/nant/2010/04/05/nants-not-dead-it-was-just-resting/