When Mozilla said last year that it was going to include a do-not-track header in its Firefox browser, the central question raised by the feature was whether any online companies would honor it. It's still not clear how online companies overall will respond to the Firefox header. But in recent weeks, a group of more than 30 ad networks and behavioral targeting companies have come forward to say that they back Mozilla's approach and are urging all other companies in the space to respect the headers.

Microsoft has added another privacy feature to Internet Explorer 9: A do-not-track header. The tool tells the Web sites that consumers visit that they wish to avoid online tracking. It marks the second new browser-based privacy feature in IE9; the first, unveiled last month, allows users to create "tracking protection lists," which allow users to block networks from serving ads on sites they don't own.

AT&T, the country's second-largest Internet service provider, intends to start imposing monthly bandwidth caps of 150 GB on DSL subscribers and 250 GB on people with U-Verse connections.

Four U.S. senators warned Facebook this week that the company could expose users to identity theft by following through on a controversial plan to allow app developers to access users' phone numbers and addresses.

Lawmakers who want to see neutrality rules overturned might be able to muster enough votes to do so in the House, but it's unlikely that they will prevail in the Senate. Nonetheless, that's not stopping certain members of the GOP from continuing to rail against open Internet rules -- and to make some extremely questionable arguments in the process.

Last year, when former Las Vegas Review-Journal publisher Sherman Frederick wrote that his company had "grubstaked" copyright enforcement outright Righthaven, he publicly urged other newspapers to join the new litigation initiative. At the time Righthaven had filed 22 copyright infringement lawsuits against bloggers, small publishers and nonprofits who allegedly reposted all or parts of Review-Journal articles. Since then, Righthaven has filed more than 200 additional cases, but hasn't garnered many takers for its offer to represent other papers in copyright lawsuits.

Republicans in the House Energy Committee are stepping up the rhetoric against the Federal Communications Commission's new neutrality rules in advance of tomorrow's hearing about whether the regulations should be vacated.

A federal judge in California has issued a ruling that should alarm privacy and free speech advocates. The order, by Magistrate Judge Joseph C. Spero, allows Sony to obtain the IP address of all people who visited the site of hacker George Hotz since 2009. The order also allows Sony to discover other information, including the IP addresses and user names of visitors who streamed a private YouTube clip after Jan. 27.

A judge in Indiana has ruled that two newspapers must turn over IP addresses and other information that could identify an online commenter who allegedly criticized a local businessman.

The free speech advocacy group Reporters Without Borders today asked Denver Post parent MediaNews to reconsider its decision to tap copyright enforcement outfit Righthaven to sue bloggers.