The Electronic Frontier Foundation (EFF) has confirmed the AP story regarding Comcasts malicious packet injections.

“The results of our tests have agreed with AP's. Comcast is forging TCP RST packets which cause connections to drop (a technique also used by Internet censorship systems in China). These packets cause software at both ends to believe, mistakenly, that the software on the other side doesn't want to continue communicating.

The TCP RST packet forging seems to be protocol-specific: as AP reported, it at least sometimes happens directly in response to specific BitTorrent protocol events. This contradicts Comcast's statement to us that their network management does not target or discriminate against particular protocols. The timing of the injected packets suggests that something on Comcast's network understands the BitTorrent protocol and treats it differently from other protocols.” 

 

Several months ago Comcast stated that they do not interfere with traffic (link).

I think this is bad especially since Comcast operates as a monopoly in several markets.