This is because automount (autofs), is running, you can disable the "/home" if you need by edit "/etc/auto_master" and comment that map:
..
# Master map for automounter
#
+auto_master
/net -hosts -nosuid,nobrowse
#/home auto_home -nobrowse
/xfn -xfn
then stop/start autofs by:
# /etc/init.d/autofs stop
# /etc/init.d/autofs start
now "/home" is writeble...
If you are not using automounter facilities you can aloso disable it.
Regards,
Carlos Almeida.