I think on the API docs when it says Public API's it means public in the OO sense (as in they are available for applications to use them).
Since you can't get those components without installing LCDS (and they are in fact integral parts of it), I imagine it would be covered by the standard licensing terms. Maybe someone else can confirm or refute this?
Looks like things have changed a bit since last week when I posted.
With the announcement yesterday of BlazeDS (scheduled for release 2008), it seems the libraries mentioned will be available under the LGPL v3, so I believe you may be able to redistribute them (unmodified and probably as a separate installer/archive) under the terms of the LGPL.
It sounds like there will be some features not included in the OSS version of Data Services, but from reading the FAQ it seems that the messaging API you mentioned will be included in the LGPL licenced version.