I think this would do it, modify similarly for 2011.
Not sure if there is a more stable place to find it, like a package receipt or not. With an explicit path like this you have to hope all machines are alike.
#!/bin/sh
??Office08Version=`/usr/bin/defaults read /Applications/Microsoft Office 2008/Microsoft Word.app/Contents/Info CFBundleVersion`?
echo "<result> $Office08Version </result>"??
exit 0
Or, since your collecting this via recon anyway, you could make smart groups to find certain versions or use Inventory to report the same.