I think it helps to think of browsing as a basic form of searching. Everything you can do in a browsing context, you can by definition do in a searching context...if the client doesn't suck. The information needed to browse is embedded in the tags.
So this strikes me as entirely dependent on your client software. A good client should let you browse by tags. You could add Dewey numbers as tags to start with, so you can browse that way if you want, then add any other tags that might be useful (like genres, for example) on top of that.
The only difference with tags in this context is that books will appear in multiple places.