One thing I really liked about Yahoo! 360 (ask me for an invite if you have not got one) is its implementation of access control. You can choose from multiple level of privacy for different sections of your Yahoo! 360. For example, you might want everyone on 360 to see your real name, restrict your residential address to only your 2nd degree friends, and then further restrict your primary email address to your first degree friends. Access control applies to not only your basic info, but also your full profile, your "Blast", your lists and groups, and your blog.
Access control on blog is fantastic, especially when your blog is used mainly as a personal journal/diary whose writing might not be suitable for public consumption. Want only your close friends to know what you have been doing last weekend? Want to blog about your thoughts on certain complicated issues, but do not wish to share with everyone? Easy. And Yahoo! 360 does all the authentication and user management for you.
Moreover, when the privacy level is set to only your first degree friends, you can further restrict the visibility of your blog by your friend "Categories". You can allocate your friends to one or more categories, or default to "Uncategorised". Now let's see. Shall I start a personal blog there that actually blocks everyone who knows me personally from reading it?