According to an e-mail blast from Valve, a limited-time beta of Counter-Strike: Source will begin later this summer via the developer's Steam download service. Subscribers of the Valve Cybercafé Program will be the first invited to the beta, which will be extended to owners of Counter-Strike: Condition Zero at a later date.
Other than reminding the world that Counter-Strike is still "the worlds number one online action game," Valve gave no other details on the beta. However, Valve head Gabe Newell did demonstrate Counter-Strike: Source at this year's Electronic Entertainment Expo.
GameSpot will have more details on the Counter-Strike: Source beta as they become available. Half-Life 2's release date is still to be announced, although Newell recently indicated that he's hoping it will go gold in August.