If you fancy trying out the new Messaging Jelly Bean app found in the latest Xperia update, then you can now try it yourself. The apk has leaked and will work on both rooted and non-rooted Xperia devices running Android 4.0.4 Ice Cream Sandwich. Most people trying the new app report 100% success in getting it to work. You can find more details here and download the apk here.
Thanks Nabendu!