Over at GameSpy, they've got an article on about the details Valve Software decided to unveil reffering to the original Half-Life redone with the Source Engine. Here's a small sneak peek portion of the article:

"During an interview on the GameSpy LiveWire radio show this afternoon, Valve's Doug Lombardi elaborated on that process, mentioning that the original Half-Life had been ported to the new engine as part of its testing. As a result, a new version of the 1998 game, running in the Source engine, will be released around the same time as Half-Life 2."

This article also includes some info about other Half-Life game series aspects,(such as CS redone with the Source Engine), but mainly focuses on the original Half-Life redone with the source engine. It's a little short, but you can find the full article for viewing here. Enjoy! You're welcome!