PHPHead has a new news item about Chunked Output Buffering in PHP and how it can help speed up the loading of the page. For some benchmarks, check out this page.
Zend.com also has a new article about using the MM module with PHP and how it can help speed up the operations, epsecially with sessions.
And speaking of Zend, they also have the newest "Gallery Spotlight" that talks about connecting to various Internet Services. It touches on everything from connecting to other sites to connecting through sockets.