Johnson was one of those guys who mined the fertiile ground between blues and jazz; he was pigeonholed as a blues performer during his heyday, but ultimately his guitar style was just as influential in the jazz world as the blues.

Chief among his developments was the idea of 'single string' soloing, taking the guitar out of a primarily rhythmic accompaniment role. Instead of using a fingerpicking technique like most of the blues guitarists who were being recorded from 1922 on, he used a pick and played his melodies and especially his solos one note at a time.

Among the previously unexplored avenues this opened up to guitarists was the idea of the string bend, which approximated the effect guitarists were already getting using a slide but didn't require re-tuning and therefore allowed a greater flexibility.

A piece sometimes credited as 'the first guitar solo' is 6/88 Glide, from 1927, and you can hear both Johnson's fluidity, his ability to skate between what we'd recognize today as bluesy vs. jazzy, and those bent notes.

Enjoy: http://www.youtube.com/watch?v=_pV9nO6rYN4