Hi, just a small suggestion - since not everybody uses iso encoding, it would be wise to add feature to admin panel (maybe dropdown list) which will allow users to change the encoding of wp_dtree_cache table (especially content column).
Now, multibyte characters on sidebar are shown as "?" ( or something else strange) when the site is not set with iso8859-1....
The default encoding for cache table is latin-1 - its ok, but many people - like me - are using utf-8 in their databases. I altered manually the table, but not everyone would be able to do this.
sorry for english..
regards