Preliminary review
1) rpmlint on SRPM and RPMs gave me
eruby.src:9: W: buildprereq-use ruby
The use of BuildPreReq is deprecated, build dependencies are always required
before a package can be built.  Use plain BuildRequires instead.

eruby.src:10: W: buildprereq-use ruby-devel >= 1.8.0
The use of BuildPreReq is deprecated, build dependencies are always required
before a package can be built.  Use plain BuildRequires instead.

eruby.src: W: mixed-use-of-spaces-and-tabs (spaces: line 76, tab: line 1)
The specfile mixes use of spaces and tabs for indentation, which is a
cosmetic annoyance.  Use either spaces or tabs for indentation, not both.

eruby.i386: E: non-standard-dir-perm /usr/share/doc/eruby-1.0.5/examples 02755
A standard directory should have permission set to 0755. If you get this
message, it means that you have wrong directory permissions in some dirs
included in your package.

eruby-libs.i386: W: no-documentation
The package contains no documentation (README, doc, etc).
You have to include documentation files.

eruby-libs.i386: E: non-standard-executable-perm
/usr/lib/ruby/1.8/i386-linux/eruby.so 0555
A standard executable should have permission set to 0755. If you get this
message, it means that you have a wrong executable permissions in some files
included in your package.

eruby-devel.i386: W: no-documentation
The package contains no documentation (README, doc, etc).
You have to include documentation files.

eruby-devel.i386: W: no-dependency-on eruby

eruby-devel.i386: W: summary-ended-with-dot Development files for eRuby.
Summary ends with a dot.


SHOULD:
  1)Avoid .a files
  2)use %defattr (-, root, root, -)
  3)Keep consistent usage of macros
     use %__install_p, %__rm, %__cp, %__make, %__chmod.
  4)Can't see License files installed.
  5) Any reason to use eruby-all.files way of installing files in %files section?

(In reply to comment #1)
> eruby-devel.i386: W: no-dependency-on eruby

No problem because eruby package provides a program and a library and -devel
package doesn't requires a "program" to develop eruby application.

Updated files are available at:

Spec File: http://tagoh.fedorapeople.org/eruby/eruby.spec
SRPM File: http://tagoh.fedorapeople.org/eruby/eruby-1.0.5-10.src.rpm

Review:
+ package builds in mock (development i386).
+ rpmlint is silent for SRPM but not for RPM.
  eruby-devel.i386: W: no-dependency-on eruby
+ source files match upstream.
af294fe34dc6cf24228aec95167b3099  eruby-1.0.5.tar.gz
+ package meets naming and packaging guidelines.
+ specfile is properly named, is cleanly written
+ Spec file is written in American English.
+ Spec file is legible.
- dist tag is NOT present.
+ build root is correct.
+ license is open source-compatible.
+ License text is included in package.
+ %doc files present.
+ BuildRequires are proper.
+ Compiler flags are honoured correctly.
+ defattr usage is correct.
+ %clean is present.
+ package installed properly.
+ Macro use appears rather consistent.
+ Package contains code.
+ no static libraries.
+ no .pc file present.
+ -devel and -libs subpackage exists.
+ no .la files.
+ no translations are available.
+ Does owns the directories it creates.
+ no duplicates in %files.
+ file permissions are appropriate.
+ ldconfig scriptlets are used.
+ Package eruby-1.0.5-10 ->
    Requires: libc.so.6 libc.so.6(GLIBC_2.0) libc.so.6(GLIBC_2.3.4)
libc.so.6(GLIBC_2.4) libcrypt.so.1 libdl.so.2 liberuby.so.1.0 libm.so.6
libpthread.so.0 libruby.so.1.8 rtld(GNU_HASH)
+ Package eruby-libs-1.0.5-10 ->
    Provides: eruby.so liberuby.so.1.0 ruby(eruby) = 1.0.5
    Requires: libc.so.6 libc.so.6(GLIBC_2.0) libc.so.6(GLIBC_2.1.3)
libc.so.6(GLIBC_2.3) libc.so.6(GLIBC_2.3.4) libcrypt.so.1 libdl.so.2
liberuby.so.1.0 libm.so.6 libpthread.so.0 libruby.so.1.8 rtld(GNU_HASH)
ruby(abi) = 1.8
+ Package eruby-devel-1.0.5-10 ->
    Requires: liberuby.so.1.0 ruby(eruby) = 1.0.5
+ Not a GUI app.

APPROVED.

Thanks for reviewing. the updated package has been built on koji.