plexus-compiler-*-1.5.1.jar not available in remote repo

[cheethus]

m2 looks for plexus-compiler-*-1.5.1.jar series of jars in the remote repo.
http://www.ibiblio.org/pub/packages/maven2, but could not find them and
hence build fails. I tried pointing to 1.5 versions(which is available in
remote repo), but the problem still persists. Any idea where I can get these
from? Is it really required?