build-war.xml

<target name="war" depends="compile" description="--> generate project's war">
	<delete file="${artifacts.dir}/${war.file}" />
	<copy todir="${tmp.classes.dir}">
		<fileset dir="${resources.dir}" />
	</copy>

	<war destfile="${artifacts.dir}/${war.file}" webxml="${webapp.dir}/WEB-INF/web.production.xml" compress="true" >
		<fileset dir="${webapp.dir}">
			<exclude name="WEB-INF/web*.xml" />
			<exclude name="**/servlet*.jar" />
		</fileset>
		<classes dir="${tmp.classes.dir}" />
	</war>
</target>

build.xml

<project name="project-name" default="compile">
	<description>Build full</description>
	<property file="build.properties" />
	<property name="war.file" value="${war.filename}.war" />

	<path id="libs.classpath" path=".">
		<fileset dir="${libs.dir}">
			<include name="*.jar" />
		</fileset>
	</path>

	<path id="compile.classpath">
		<path refid="servlet-api.classpath" />
		<path refid="libs.classpath" />
	</path>

	<target name="compile" depends="prepare" description="--> compile the classes">
		<javac destdir="${tmp.classes.dir}" srcdir="${src.dir}" classpathref="compile.classpath" debug="true" encoding="UTF-8">
		</javac>
	</target>

</project>

build_compile_and_copy.xml

<copy todir="${tmp.classes.dir}">
	<fileset dir="${resources.dir}" />
</copy>

GemPackageTask.rb

Rake::GemPackageTask.new(spec) do |pkg| 
  pkg.gem_spec = spec 
end

Rakefile.rb

require 'rake'
require 'rake/testtask'
require 'rake/rdoctask'
require 'rake/gempackagetask'

desc 'Default: build gem.'
task :default => :package

PKG_FILES = FileList[ '[a-zA-Z]*', 'generators/**/*', 'lib/**/*', 'rails/**/*', 'tasks/**/*', 'test/**/*' ] 

spec = Gem::Specification.new do |s|
   s.name = "Relata"  
   s.version = "0.0.2"  
   s.author = "Anderson Leite, Guilherme Silveira"  
   s.email = "anderson.leite@caelum.com.br"  
   s.homepage = "http://github.com/caelum/relata"  
   s.platform = Gem::Platform::RUBY 
   s.summary = "Helps poking around with relationships when using ARel"
   s.files = PKG_FILES.to_a 
   s.require_path = "lib"  
   s.has_rdoc = false 
   s.extra_rdoc_files = ["README.markdown"] 
end 

desc 'Turn this plugin into a gem.' 
Rake::GemPackageTask.new(spec) do |pkg| 
  pkg.gem_spec = spec 
end