Microsoft has placed an age restriction on access to Twitter, Facebook and Last.fm in the public preview of the applications on Xbox Live but is working on an update that will let parents control which applications their children can access.
Microsoft announced the public preview of the upcoming Xbox Live services in October. Unfortunately for gamers of a certain age (which is to say, under 18), the company wants to ensure an "age-appropriate environment" for everyone and since the Family Settings options don't allow parents to selectively restrict the applications, Microsoft imposed across-the-board age limits on Twitter, Facebook and Last.fm.
Those limitations will stay in place when the applications are given a full launch, at least until Microsoft can issue an update which will give parents full control over access to them. Major Nelson said the development team is working on implementing the controls and while no date is given, he added that Microsoft hopes to get the update out "several weeks" after the applications launch.