Not exactly Ruby, but since you have web development experience, you could as a start, learn Ruby via Rails. That way, you will get to see Ruby in context of web-development and maybe will help you learn faster. Then, look for a book on Ruby itself (I'm looking for one too, so thanks for your question :)
I learned a lot from
Agile Web Development with Rails
(2nd edition)
Beginning Rails:
From Novice to Professional
I found book #1 very helpful when first reading about Rails. But wanting to get more advanced, it doesn't take you far.
Book #2 is really good too. I suppose the combination of the two taught me a lot
of details that the other book didn't cover.
For Ruby, one very handy reference book is Ruby in a Nutshell. I have this edition but a newer one for 1.9 should be there too. Reading just that book I picked up quite a few clues on how Ruby works.