I wish I'd seen this thread when it was active, a couple of years ago! I created an account mainly to write a couple of responses to people who might end up here in the future - and on a related note, huge thanks to LordoftheStrings for the links!
So, to all the people who think Guthrie doesn't have a signature, I must urge you to consider two points:
1. Most people judge a signature by the techniques that the guitarist most often uses (and possibly has pioneered), and to an extent the tones. What's actually deeper is the touch-and-feel of the guitarist in question - how he physically treats the strings, with both hands. A perfect example for this would be Jeff Beck - he'll play two notes and you'll know it's him, and not because of technique. With Guthrie, you cannot judge via the standard techniques, because he's exceptionally good at all of them - if you have the ears of a guitarist, you should be able to hear his own higher-layered technical improvisations, but for that you need a lot of samples, which brings me to the second point:
2. You should realise that Guthrie isn't particularly interested in recording dozens of studio albums, and that's the hint that he isn't as much of a studio musician as he is a live one - watch his improvs, jams, tutorials, rig demos, interviews, etc. and you'll start noticing a few patterns in his style and treatment of music. Once you start getting in the groove, I'd recommend listening to both The Aristocrats
albums that are out (at the time of this writing), multiple times, and then watching them live - be it on YouTube or live (I'm not in a continent where musicians usually perform, so I don't really have an option, but if you can catch them - go!). Hopefully, by then you'll have developed the ear to pick up tiny nuances that are nevertheless strong and have depth, and also have had a rather vast exposure to his signatures.
Links start here
If you've heard Erotic Cakes and remember Fives, hear this rendition http://www.youtube.com/watch?v=7uPJ1Qa3xC8
where he plays along with Tal Wilkenfeld.
Here are two looper jams that are 100% improv and bloody kick-ass:
This is The Aristocrats playing Flatlands live http://www.youtube.com/watch?v=G0cVyPExfIY
, a ballad, slowed down and with beautiful dynamics throughout the piece by all three.
If you want to see them be the Monty Pythons of music, here's the pig and chicken spank (bootleg, though): http://www.youtube.com/watch?v=OTcBDx1zFXw
And lastly, here's a really spunky, fun tune where they put in humour effortlessly:http://www.youtube.com/watch?v=Oc5LkSc7DvU
If after all this you still feel Mr. Govan is more of a "YouTube artist", then I'm afraid you've been successfully capitalised by what sells (G3 and shit). Try watching these videos by YouTube artists (they don't really exist anywhere else) and tell me if your commercial Sony BMG albums are better:
Muris Varajic - Silent Inner Cry https://www.youtube.com/watch?v=CxoCYuS5ttY
Tom Quayle - Giant Steps Improv https://www.youtube.com/watch?v=GU37RyrVfok
Tom/Andy/Martin/Rick - Suhr Mega Jam https://www.youtube.com/watch?v=pNY9gJtNd6s
(Mainly Tom Quayle and Martin Miller)
Alex Hutchings and Jack Thammarat - Drivin' Blues jam https://www.youtube.com/watch?v=Syb7A3k3UL8