It's no secret that Citrix is planning on moving large parts of the Citrix farm configuration into Group Policy. One of the many reasons for doing this is that you could build a new server, drop it into an OU, and have it preconfigured for use. While this group policy based farm configuration won't be coming for a year or two, there's some important things that Juliano has discussed in a blog entry with respect to how you get from IMA-based farm/server config to Group Policy based farm/server config.
Essentially what Citrix is planning on doing is creating a Migration Utility that would read the farm information from your current PS 4.5 environment, export the entire thing to an XML file (which you could then edit to make minor modifications and then import it into the new XenApp environment that is Group Policy based. While I applaud Citrix's thoughts in this manner, I also feel like this type of utility is about 7 years overdue. If a farm migration Wizard existed back in MetaFrame XP, or 3.0, or 4.0, or 4.5 I think there's a number of farm migrations that would have been dramatically simplified. Instead, various people in the industry have created their own scripts and applications to perform these functions.
Regardless of that, I do agree with the approach and I definitely recommend reading Juliano's blog entry on this topic as ultimately it will become the de facto standard way of doing farm migrations so speak now or forever hold your peace.