Last night I found out that the Woodstock text field component now supports autocomplete. I figured that since the version of Woodstock included with NetBeans 6.1 RC1 is the one that introduced this functionality, that it would be fairly trivial to implement this using Visual Web.
Today I tried out my theory and unfortunately it turned out I was wrong. I essentially followed an example by Dmitry Kushner, but skipping the part about adding library dependencies, since they are added automatically to any NetBeans Visual Web project.
After creating my simple test application and deploying it, Firebug reported some Javascript errors every time a character was entered into the text field.
Apparently some of the libraries included with NetBeans are not the correct version necessary to support autocomplete.
Hopefully NetBeans 6.1 final will include this functionality.