According to a new report
(PDF) from the Pew Center for the American Life Project, some one-third
of online Americans (36% to be exact) regularly consult Wikipedia. This
reflects 8% of the broader population.

Drilling down further, Wikipedia is more popular among the
well-educated. Some 50% of those with at least a college degree consult
the site, compared with 22% of those with a high school diploma. Pew
also looked at demographics: 44% of Americans ages 18-29 use Wikipedia
to look for information, while just 29% of users age 50 and up.

The Pew Report also includes fresh data from Hitwise that reveals
just how popular Wikipedia is and how Google and search engines factor
in.

Source: http://www.micropersuasion.com/2007/04/pew_onethird_of.html

When I post my sermon notes over at my personal blog, I have found links I have included to Wikipedia to be well received.  (These have been to be to learn more about a concept, event, or person.)  Even if people do not click over, the fact you give them the ability to explore for themselves speaks to your credibility.

So make Wikipedia a part of the toolbox you use with your church.