Here is my setup:  
    Mac OS 10.4.10
    Intel MacBook Pro
    qt-mac-opensource-src-4.3.1
    qwt-5.0.2
    qt4-qtruby-1.4.9
    ruby-1.8.6
    cmake-2.4.7

I compiled Qt, Qwt, qtruby, Ruby, and cmake all from source.  I used MacPorts 1.520 to build libdbus-1.3.2 for dbus
support in Qt4.  I manually copied
    ~/qt4-qtruby-1.4.9/ruby/qtruby/src/qtruby4.0.0.0.so 
 -> /usr/local/lib/ruby/site_ruby/1.8/i686-darwin8.10.1/qtruby4.bundle

From the irb prompt, I obtain the following results:

  Compiling ruby search path...
  Setting random seed.
  Done.
  Welcome, formwalt.
  irb(main):001:0> require 'Qt'
  /usr/local/lib/ruby/site_ruby/1.8/i686-darwin8.10.1/qtruby4.bundle: warning: no super class for `Qt::Base', Object
assumed
  /usr/local/lib/ruby/site_ruby/1.8/i686-darwin8.10.1/qtruby4.bundle: [BUG] Bus Error
  ruby 1.8.6 (2007-03-13) [i686-darwin8.10.1]

  Abort trap  

I am unable to use qtruby thus far.

Date: 2007-08-31 08:55
Sender: Byron Formwalt

Vincent brings up a good point.  The 'cmake -spec macx-g++
.' command sets up the Makefiles to ultimately produce an
output library (bundle) named 'qtruby4.0.0.0.so' instead of
'qtruby4.bundle'.  Hence, the following output is generated
upon issuing 'make && make install':

[root@7:~/Desktop/Downloads/Qt_Ruby_Stuff/qt4-qtruby-1.4.9]
#  make install
[ 51%] Built target smokeqt
[ 58%] Built target qtruby4
[ 65%] Built target qtrubyinternal
[ 95%] Built target rbuic4_bin
[100%] Built target rbrcc
Install the project...
-- Install configuration: ""
-- Install configuration: ""
-- Install configuration: ""
-- Installing /usr/local/lib/libsmokeqt.2.0.0.dylib
-- Install configuration: ""
-- Install configuration: ""
-- Install configuration: ""
-- Installing /usr/local/bin/rbqtapi
-- Installing /usr/local/bin/rbqtsh
-- Install configuration: ""
-- Installing
/usr/local/lib/ruby/site_ruby/1.8/i686-darwin8.10.1/qtruby4.so
install_name_tool: can't open file:
/usr/local/lib/ruby/site_ruby/1.8/i686-darwin8.10.1/qtruby4.0.so
(No such file or directory)
-- Install configuration: ""
-- Installing /usr/local/lib/ruby/site_ruby/1.8/Qt.rb
-- Installing /usr/local/lib/ruby/site_ruby/1.8/Qt4.rb
-- Installing /usr/local/lib/ruby/site_ruby/1.8/Qt3.rb
-- Install configuration: ""
-- Installing /usr/local/lib/ruby/site_ruby/1.8/Qt/qtruby4.rb
-- Install configuration: ""
-- Installing
/usr/local/lib/ruby/site_ruby/1.8/Qt/active_item_model.rb
-- Installing
/usr/local/lib/ruby/site_ruby/1.8/Qt/active_table_model.rb
-- Install configuration: ""
-- Install configuration: ""
-- Installing /usr/local/bin/rbuic4
-- Install configuration: ""
-- Installing /usr/local/bin/rbrcc

Date: 2007-08-31 08:49
Sender: Byron Formwalt

This problem was due to linking against the wrong libraries.
 It was solved by deleting all files matching the pattern
libruby* and then re-installing ruby.  qtruby4 now works
with this configuration and I get the following from irb:

    Compiling ruby search path...
    Setting random seed.
    Done.
    Welcome, formwalt.
    irb(main):001:0> require 'Qt'
    => true

Date: 2007-08-31 08:04
Sender: Vincent Fourmond

Why did you have to copy the qtruby4 bundle ? make install didn't
work propension ? Do you have some other Qt stuff in
/usr/local/lib/ruby/site_ruby/1.8/Qt ??

That sounds weird. What happens with require 'Qt4' ?