Allen Bauer has posted on his blog interesting information about Unicode support in the next version of Delphi, codenamed Tiburon. You can find the first post here and some clarifications here.
In particular notice there will be a new reference-counted UnicodeString type, based on the UTF16 payload, used to call into the wide version of the Windows API, likely to create some incompatibilities with existing code.
Now, when I can start writing my new "Delphi Unicode Handbook"?