Thank you for your question.
The treeview will have XML serialization / deserialization in Q2 2007, which is due in September. The only non-serializable part will be the controls that are hosted inside a treeview, as the Control class is not serializable.
This feature is already developed and is currently in initial testing phase. In case you want to test it for your case, please open a support ticket and request the latest treeview build - we will gladly send it to you..
All the best,
the Telerik team