The reasons for the ban on Wikipedia expand further than those that this blog has half-refuted.
First, I will admit that the new features do indeed make Wikipedia more reliable. Some studies have gone so far as to say that it is as reliable, or more so, than a typical encyclopedia.
Which leads me to another point. In my English class, ALL general encyclopedias are banned from a works cited page. Yes, the teacher will allow us to look to the general encyclopedias and even Wikipedia for our initial research to get an overview of a topic. Wikipedia just cannot provide the in-depth information that is required to construct a well-reasoned, thorough paper.
As for using Wikipedia to research more obscure topics, I ask: If the topic is so obscure that there simply are no resources about it, how did someone amass enough information for a Wikipedia entry?
Finally, the teachers banning Wikipedia are not doing so out of fear of the "new." You refer to ther teachers as being "wedded to textbooks and more standard encyclopedia entries." In reality, though, most teachers I know are not "wedded," as you say, but actually promote the usage of internet resources. My own school provides access to online databases such as EBSCOHost and Opposing Viewpoints that provide much more detailed information than Wikipedia with the same ease of use and up-to-date information.
Wikipedia has its place in research. When a person is performing initial research to develop a thesis, Wikipedia works well to provide a quick overview. Additionally, the links section at the bottom of the page can provide quick access to better, more detailed sources.
Maybe some of the stigma against Wikipedia is undeserved, but as a student I believe that the ban is justified. Wikipedia can never take the place of sources that are more reliable and more detailed.
Speaking at a conference in the UK the other day, Wikipedia founder Jimmy Wales poured it on pretty thick against teachers who ban the IMHO overly-criticized online encylopedia Wikipedia 
in the classroom.
“You can ban kids from listening to rock ‘n’ roll music, but they’re going to anyway,” the BBC website quoted Wales as saying. “It’s the same with information, and it’s a bad educator that bans their students from reading Wikipedia.”
Jimmy then added that due to enhanced procedures to flag inappropriately cited and inaccurate entries, Wikipedia is more reliable then they were before.
Listen to me now. As a former college instructor, the boyfriend of a 29-years-in teacher and someone who has been paid to perform and present objective research for over thirty years I declare that:
Teachers wedded to textbooks and more standard encyclopedia entries need to understand that Wikipedia’s subject depth as well as speed-to-entry are not minuses but pluses.
These attributes are simply irreplaceable for students who are researching obscure or fast-changing topics. And given Wikipedia’s ubiquity, why deny students the opportunity to use and then vet what, arguably, is the most commonly accessed and available reference work in the world?
And it’s not that Wikipedia entries are thrown together and only cite one side of an issue. The Wikipedia entry for Skype, for example, has a lengthy section on”Criticisms.” A student researching Skype will not be able to obtain such a comprehensive foundation of understanding by going to the Skype site, hitting the message boards, or even using Skype.
Yes, I know. Too many students are lazy, and will- if left to their own devices- do a non-attributed cut-and-paste from Wikipedia entries to term papers. That’s slovenly, and should definitely be called out.
So should students who use Wikipedia as their only source. At the very least, such students should be encouraged to use standard encyclopedias, accounts from reputable news organizations (sometimes mentioned in Wikipedia entry footbotes), professional journals, respectable magazines or books.
We live in a world where sources disagree sometimes. I believe use of Wikipedia as one of multiple sources in classrooms or term papers would go a long way toward fostering critical thinking skills.
Skills, BTW, that are taking a back seat to the damn “teach to the test” imperatives of (cough, wretch, grrrr,etc.) No Child Left Behind).
But if a Wikipedia entry is one of several cited sources, then why not?
