From Steam Update News:
Soon, we"ll be releasing the first in a series of updates to Counter-Strike: Source which will be focused on moving the core Counter-Strike gameplay forward
The first update will include an updated version of the map Train, which will feature an HDR lighting pass, some minor layout changes, and a number of small bugfixes
The second facet of this release will be a completely reworked radar system. There will be a significant change to the aesthetics of the radar, but there are also some fairly significant gameplay ramifications to the new system. One example: when you look directly at an enemy for a long enough time for their name to appear on your screen, everyone on your team will be able to see that enemy in the radar. We"re planning on releasing this first update in about two weeks