I think this belongs in both feature request and bug reports... With the beta 2 build of MegaGlest (and others previously) when you select something, the green ring shrinks around the selected object. This is an incredibly nice feature, especially when creating workers to mine gold or harvest wood.
But if you send the workers to a building which is being built, it correctly has the green circle shrink around the building, but the workers just go over and stand by the building in progress. It's a little deceptive, because it looks like they should go over and help build the building, but they don't. I think that the workers should be given the build (although I think it's actually repair) command.
You can watch it
here (video's unlisted)
The worker produced just goes over and stands by the building... he doesn't actually help build it
I don't think it's relevant to the "bug" but:
Windows 7 sp1 - 64 bit
Intel i5