I just downloaded ruby-1.4.5.tar.gz and got:
-rw-r--r-- matz/matz     12168 2000-06-20 07:08 ruby-1.4.5/ext/dbm/dbm.c

gzip: stdin: unexpected end of file
gtar: Unexpected EOF on archive file
gtar: Error is not recoverable: exiting now

My command was:
gtar -ztvf ruby-1.4.5.tar.gz

where gtar is symlinked to gnu tar.  I got it from 
http://www.ruby-lang.org/en/index.html
with netscape 4.73 on a Sun.

	Hugh
	hgs / dmu.ac.uk