Hi,
The type of book to learn UML 2.0 on depends upon your current understanding of the notation and how it is applied within a development methodology (e.g. OOA&D).
Six or so years ago when I first learnt it I used SAMS UML in 24 hours (yeh, right) and a number of others that included the UML Reference Manual and the Guide Book, UML Distilled and many others on UML 1.1. However, it wasn't until I actually attended a Sun OOA&D course that I learnt how to apply them in the correct context of the development life cycle. I didn't find any books that covered this at the time but there may be many available now.
As for UML 2.0. Once you know UML 1.x it is a simple refreshment and upgrade self-learning tasks that can be done on the job using an updated Reference Manual or specification.
There are so many books available now the ones I used (over six years ago) might no longer be the best ones.
Regards,
Ian Roberts<br />Application Architect<br />SCJP, SCJD, SCEA, OCUP Fundamental