I'm sorry if I only missed it but this is quite nice and important
feature, IMO:
Jeff Schnitzer: "There is no need to use Text in Objectify. If your
String is > 500 chars, it will automatically convert the value to and
from Text."
http://groups.google.com/group/objectify-appengine/msg/28d89b14fb797099
I think it deserves to be mentioned in the wiki-pages.
Cheers
JZ