Erik pointed out that one size doesn't fit all in terms of filtering content, even when talking about child-appropriate content. I won't debate that, nor his (kind of) tongue in cheek remark about putting advisories on the Christianity (and all other religion?) articles.
But here's where I think that argument falls down. The wikipedia is fortunately unlike almost every print encyclopedia in that one can (or will be able to, one day, we hope) find information on virtually anything. I would guess that, when people see "online, open content encyclopedia", they think in terms of information available in print encyclopedia - I imagine it this way, laugh if you like: "Hey mom, I found this really cool site!" "Really? What kind of site? (<subtext of normal parental concern>)" "It's an encyclopedia - look at this cool picture of an aardvark!" "Gee, honey, that *is* pretty cool! Useful, too!" And mom, seeing it's an educational tool, goes back to doing whatever, only to have her kid come up later and ask about the information in the Felching article (and by the way, that looks a lot like a dictionary entry to me), which might not be at all intelligible to a pre-teen, at least. I think one size does fit all when erring on the side of caution. In other contexts that same information might be seen as abusive towards the child.
Sorry - I don't want to sound like a prude or like I'm some right-wing fanatic. I just know that I live in a society that expects that, as a society, we protect our children from things they aren't equipped to handle - we try to refrain from swearing around them, we (except in the US, it seems) have a sex and violence watershed on TV, etc. If individual parents want to let their kids see R-rated films, or play super violent video games, they can (again, I think the US is actually more liberal about this). But that doesn't let the wikipedia off the hook from at least letting people know that there is information on the site that is not found in "normal" encyclopedias and is certainly not age-appropriate for young children.
By the way, is anybody referring to articles OTHER than the ones with explicit sexual (in any variety) details? I can see an argument for the nightly news not being appropriate for young kids, too, but at least parents have a good idea of what will be shown - I thought I did, till they showed a cop being murdered by somebody at a routine road stop.
Julie