Hey, Tim.

Originally Posted by: TimRetallackIm interested in learning how different people handle fourths, which involve either an excessive stretch with your fretting hand, or going from one string to the next.[/quote]
It depends on the application.

If it's a fast single note line, then I'll usually do the stretch. Especially, in a rock or jazz context.

But a slower line, like a blues or pop thing, especially with a pentatonic based shape I'll roll my finger from one string to the next much like you wrote:
[QUOTE=TimRetallack]
... lay your finger down on the next string while going up ...
... finger the string with fingertip to spare while going down and roll it onto the lower string ...

The other part is the picking hand muting. That is an essential part of the technique as well. So as you roll your fingertips on you fretting hand, you have to adjust the muting with your picking hand palm.

This technique is part of what is necessary in sweeping, too! Look here for more:

http://www.guitartricks.com/tutorial.php?input=985
http://www.guitartricks.com/tutorial.php?input=1000
http://www.guitartricks.com/tutorial.php?input=1019

Ask more as necessary, let me know how it goes. Have fun!