There was a large section devoted to Alan Turing in the BBC show QI XL (series 1 episode 13, broadcast Dec 2 2011), which features Stephen Fry and a panel of guests answering difficult but interesting questions. The theme of the recent show was "intelligence." During this there was a question on Enigma which was used as a lead into Alan Turing. Stephen Fry brought up the subject of Apple's logo (an Apple with a bite out of it) allegedly being in honour of Alan Turing, who died after purposefully eating an apple poisoned with cyanide. Stephen Fry recalls asking Steve Jobs (they were friends) if the rumours were true. Jobs replied, “It isn't true, but God we wish it were!” So finally and officially, right from the horses mouth as it were, this rumour is debunked. However, there is no harm in remembering Turing when you look at Apple's logo.
The episode of QI XL can be viewed in the BBC iPlayer if you live in the UK.
Update: The British Comedy Guide now confirms this and it has appeared on Turing's Wikipedia entry.