But I wonder: Why have you split the project into a 32-bit and a 64-bit package? Wouldn't it be better to build it with an "Any CPU" platform profile? Or maybe just add the AnyCpu in addition?
...
<target name="build" depends="clean, compile, compile64, compileAnyCpu, deleteLog4netXml" />
<target name="publish" depends="test, build, zip, zip64, zipAnyCpu, package, package64, resetNuspecVersion" />
...
<delete dir="${dir.binAnyCpu}" if="${directory::exists(dir.binAnyCpu)}" />
...
<target name="compileAnyCpu" description="compiles the project in AnyCPU mode">
<exec program="${framework::get-framework-directory(framework::get-target-framework())}\msbuild.exe"
commandline=""${file.project}" /p:Configuration=Release;DocumentationFile=LinqToExcel.xml;Platform="Any CPU";OutputPath="${dir.binAnyCpu}\\"" />
</target>
...
<target name="zipAnyCpu" description="zips the contents of the bin64 folder to the zip.dir64" depends="setVersion">
<zip zipfile="${dir.base}\LinqToExcel_AnyCpu_${publish.version}.zip">
<fileset basedir="${dir.binAnyCpu}">
<include name="**/*" />
</fileset>
</zip>
</target>