QUOTE(thouston @ Mar 8 2012, 12:51 PM)
Not a teacher, but first hand experience of self teaching (admittedly, having learnt "properly" a long time ago).
First and most important thing is: what sort of music does he want to play? This has a bearing not only on what sort of guitar to get him: classical (nylon string), acoustic (steel string), or even rock (electric), but also what resources to go for. It's not really possible to recommend any books without being clear about this - classical technique will be of no interest whatever if he wants to learn screaming electric solos...
That aside, I have actually found some really good stuff on You Tube, which has everything from ABRSM scales and pieces to rock riffs. Just search "learn to play guitar" or the name of an actual song, or "ABRSM guitar scales" and you'll see what I mean. (there's a great video that michael_N posted in the Adult Learners section, entitled "How to improve!" which is just one example).
I imagine that you want an actual "thing" (book, DVD) that you can hand over to make it more of a gift, but without more info an what guitar and style he wants it will be difficult for anybody to recommend anything.
Well, he doesn't know he's getting it, but I would imagine she won't be thinking of classical with him in mind. I don't know what he was trying to play the last time he had the guitar, but, you know, some people actually don't know what they want to play! They just think the guitar would be a cool idea. Not electric, certainly, he's too laid back to be wanting to do "screaming electric solos" (He's also in his mid-30s, not that that will exclude the screaming and head-banging, but he doesn't do tht)
I think if I were doing this "blind" I would be going for folk/acoustic, because it's more adaptable.
And yes, she does want a "thing" to give him. Anything which seems to say "learn yerself guitar" will do, but I wondered if anyone could give me a recommendation that they've tried.