I could read before I went to school - I went at 4.3 and had been reading a good while before then and was learning to write when I went - I can clearly remember sitting on the floor and trying to make the shapes from words I could read and getting very frustrated when I couldn't.
DS1 learnt the alphabet (in capitals) from Countdown in the weeks after DS2 was born - he was 21mo then.
By the time he was 2.2, he was recognising logos reliably - Homebase, Tesco, Sainsbury's, Argos, Fifi Flowertot(!), B&Q, PC World, Boots - if we'd been in the shop, he knew the logo. When he was 2.4, we went on a 2.5 hour car journey and DH laminated him a sheet with shop logos and makes of car on to entertain him on the journey spotting the different places - he loved it!
He's 3.1 now and knows the lowercase letters as well as capitals and can recognise his name. He loves "touching the letters" at the end of TV programmes - will go and stand and watch the letters scroll between his fingers.
He has access to books all day, he likes reading them, we read to him (not as often as we ought, probably, but fairly regularly).
But he can't read - as others have said, to read you need to be able to work out a novel word, not one you've memorised. He just likes words, logos in particular. I'm sure if I'd spent hours teaching him, he'd be able to read by now, but I can't be arsed and he'll learn soon enough!
I went to school during the look and say method being popular and it was a fine way to teach me, because I didn't need teaching. I could spell words I'd never heard or seen before - I've almost never made a spelling mistake in my life, just because I "know" when a word looks right. It means I've always done proof-readery jobs because I find them very easy - I can scan a page of text and the spelling mistakes are almost circled in red as I skim it.
Just don't ask me to do long division I think I got too many language genes and NO number ones!