Steam News offers an update on the Half-Life 2 stuttering bug, as well as promised of the release of the Half-Life 2 SDK and a "surprise" soon:

The changes in this release are directed at reducing the problem some users are experiencing with sound stuttering. The sound stuttering is not indicative of a sound problem, sound stuttering is only a symptom of texture thrashing on your video card or AGP memory. For information on how to reduce texture thrashing visit this link on our support site:

http://steampowered.custhelp.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=280

This update will fix sound stuttering that users were experiencing that would last for longer than a few seconds during normal gameplay. This update will also eliminate this same behavior following a quicksave or autosave. There will still be a short pause while the autosave happens, but not the more drawn out stuttering behavior.

We are still investigating another performance problem on some hardware, which will manifest where the game is getting into a state where performance drops to less than 5 fps and does not recover or crashes.

Next week we will be releasing the Source SDK, along with a surprise for the community.