Note 109: Some of the internal Delphi tools like the WebAppDebugger or the DataSnap socket connectivity still rely on Indy 9. This is why you'll get in trouble if you try to use Indy 10 in a project that also requires these tools and components.
This blog post is part of my "113 Delphi 2007 Handbook Notes" blogging project, to promote my new Delphi book.