Ayende's current post series is covering a topic of great interest for our desire to allow changes to RavenDB-persisted object definitions to occur relatively painlessly. Just figured to share in case anyone missed it 
http://ayende.com/blog/66563/ravendb-migrations-rolling-updates?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+AyendeRahien+%28Ayende+%40+Rahien%29