Our son learned to read very early (age 2.5) but we didn't teach him. I knew he wanted to learn to read, because he was sitting in my lap for hours on end while I read every book in the house to him. So, I made sure that we had lots of good books around for him. Not just good books. Wonderful books, tantalizing books, amazing books. I pored over the Chinaberry catalog, browsed through amazon listmania lists, and talked to every book fiend I knew. We went (and still go) to the library once a week to pick out new books. Sam would ask me to read to him all the time, and I would. As often as he asked. It was something that, for whatever reason, he wanted to figure out, and he did. We never did any of the teaching-reading books, although I have heard good things about some of them.
If your toddler wants to read, he will. My advice would be to keep tons of great books around for him.
Have fun! I found that seeing Sam plunge into reading was the coolest thing ever.