Filtering of Internet content has taken a new dimension in Philadelphia.
Let us not confuse CIPA filtering requirements with classroom management issues.
Some facts and some thoughts (a draft message in response to an inquiry about blocked sites):

Filtering Requests
The School District of Philadelphia has established a new process for submitting and reviewing internet filtering requests. This process is made necessary by the intent of CIPA and the needs of our teachers and students to have access to appropriate, accurate, and timely information.
Many of the requests must be denied simply due to the obvious inappropriate content housed on the site. Many must be blocked due to network security issues.
Appropriate educational content is a fluid thing and we have attempted to make this process responsive to the needs of our educators and learners.
Our committee consists of four members from Teaching and Learning, three members from Educational Technology all weigh in on content appropriateness,, and one from Technology services to inform on technical issues.
We are compiling Best Practices and FAQ documents to help our teachers make better, informed decisions on their internet usage/practices.
For example, we have had many requests to unblock YouTube. This is an obvious one: YouTube does not categorize/filter any of it’s content – students will be able to view content that is clearly in violation of the intent of CIPA and related laws. If a teacher has not planned in advance and needs access to this content they are not following educational best-practices and should not be rewarded with access. The content on YouTube is clearly labeled with creator/publisher information. If this content is educationally appropriate, the teacher should contact the creator/publisher and ask for the content to be posted to YouTube.com/education(getting better every day) or TeacherTube/SchoolTube (if it is not already posted there!)
Google videos is blocked for similar reasons – if Google categorized and had tiered access to all the video content we would reconsider the request.
Twitter is open. Many teachers use it as their main PLN (personal learning network - I use plurk.com for similar reasons)
Similar scenarios apply to most of the other requests.
Streaming of radio station content is silly – it's un-necessarily clogs our network resources and can be utilized more appropriately using a radio (or recorded for playback later).
Members of the committee are available for consultation and recommendations, if necessary.
This is a work in progress. Few educational entities have any process in place like this one – we are pioneering this idea!

Filtering Presentation PDF