The Maryland Juice blog has been following a story in which Montgomery County, Maryland's local government has instituted an overly aggressive web filter
for government employees, that seems to block all sorts of sites that mention things about gays or lesbians. And they're not just doing sitewide blocking, but picking out news articles on the subject -- suggesting that it's not just a case of an overactive blacklist of sites, but a system that specifically blocks pages with words related to gays and lesbians. For example, a CNN article about a transgendered basketball player was completely blocked.
After getting some more info on this, the blogger at Maryland Juice noticed that there was WiFi on the Amtrak train he was on, and tried to check out another news site that someone told him had been blocked by the County... and discovered that Amtrak appeared to be blocking news about gays and lesbians
This, of course, is one of the serious problems with any sort of plan for government mandated filters. They tend to significantly over-filter perfectly legitimate content that is protected free speech.