More HDR enabled maps, as well as some enhancements to the game are on the way for Counter Strike: Source. Day of Defeat: Source has a more substantial update lined up, adding a number of new features, together with a new map called Colmar. The map is the first to take advantage of Valve's new objective system, enabling the creation of different kinds of levels to those that currently exist. Specifics of this new system will be revealed at a later date.
There is of course a biggish update coming soon for Half-Life 2, with Half-Life 2: Episode 1 now less than three weeks from its June 2 release. However, we all know how Half-Life 2 missed its release date, so there's no guarantee that the game will be released on that date.