Our primary use for rails is in conversion of legacy applications to the rails framework.  As we do this in an iterative manner, we'd like to be able to replace only portions of applications with rails versions of the functionality.  In order to accomplish this seamlessly, we needed some glue to allow rails to be aware of things such as already authorized users, peristent variables, etc.  To accomplish this we came up with a patch to "php_serialize.rb":http://www.aagh.net/projects/ruby-php-serialize
.  

Here's the patch:
<pre>
<code>
--- php_serialize.rb    2004-09-17 13:46:30.000000000 -0500
+++ PHP/php_serialize.rb    2005-03-09 15:19:20.000000000 -0600
@@ -22,9 +22,13 @@
 # }}}

-# PHP serialize() and unserialize() workalikes
+# PHP serialize() and unserialize() workalikes # {{{ Docs
 #  First Released: 2003-06-02 (1.0.0)
 #  Prev Release: 2003-06-16 (1.0.1), by Thomas Hurst <tom@hur.st>
-#  This Release: 2004-09-17 (1.0.2), by Thomas Hurst <tom@hur.st>
+#  Prev Release: 2004-09-17 (1.0.2), by Thomas Hurst <tom@hur.st>
 #                Switch all {}'s to explicit Hash.new's.
+#  This Release (patch): 2005-03-09 (1.0.2.1), by The Rubyists <rubyists@rubyists.com>
+#                       added handling for php session files with PHP.parse_session
+#                       as well as a hook in PHP.unserialize to recognize strings which
+#                       are sessions.  Disregards objects stored in sessions.
 #
 #  These two methods should, for the most part, be functionally identical
@@ -78,7 +82,7 @@
 #   classmap.
 #
-# Note: StringIO is required for unserialize(); it's loaded as needed
+# Note: StringIO is required for unserialize(); it's loaded as needed # }}}
 
-module PHP
+module PHP # {{{
    def PHP.serialize(var, assoc = false) # {{{
        s = ''
@@ -147,4 +151,7 @@
    def PHP.unserialize(string, classmap = nil, assoc = false) # {{{
        require 'stringio'
+       if pipe = string[/^[^:]*:/].index("|")
+           return PHP.parse_session(string)
+       end
        string = StringIO.new(string)
        def string.read_until(char)
@@ -159,7 +166,8 @@
 
        do_unserialize(string, classmap, assoc)
-   end
+   end # }}}
 
-   def PHP.do_unserialize(string, classmap, assoc)
+private
+   def PHP.do_unserialize(string, classmap, assoc) # {{{
        val = nil
        # determine a type
@@ -257,8 +265,20 @@
        val
    end # }}}
-end
+   
+   def PHP.parse_session(sessionstring) # {{{
+       $; = /\w+\|/
+       names   = sessionstring.scan($;)
+       objects = sessionstring.split[1,sessionstring.split.length]
+       count   = -1
+       structs = names.map do |name| 
+           count += 1
+           { name.sub(/\|$/,"") => PHP.unserialize(objects[count]) } if objects[count][0,1] != 'O' 
+       end.select { |f| f != "" }
+       structs
+   end # }}}

+end # }}}

-if $0 == __FILE__
+if $0 == __FILE__ # {{{
    require 'tempfile'

@@ -306,4 +326,4 @@
        tmp.close!
    end
-end
+end # }}}

</pre>
</code>

<h3> Usage </h3>
<pre>
<code>
sessPath = "/var/lib/php4"
sessFile = sessPath + "/sess_" + @cookies['PHPSESSID'][0]
phpVars = PHP.unserialize(File.read(sessFile))
</code>
</pre>

This will return everything except for php object into the phpVars instance.  Next step is to add dynamic creation of ruby objects from the stored php objects, if possible.  Any help would be greatly appreciated.  The full module source with patch applied is available:
"php_serialize-1.0.2.1.rb":http://bougyman.com/miscfiles/php_serialize-1.0.2.1.rb

For a similar project (and we would be willing to collaberate) see UsingRailsToGraduallyReplaceARunningPHPNukeInstallation