I have been working a lot with Web Deployment Projects and even wrote articles on it, so I wanted to have a look at what comes with VS2008.
It appears that unlike what I thought, Web Deployment Projects will not be part of VS2008.
According to the Web Development Tools Team's blog:
"We are planning to release and update of Web Deployment Projects for VS 2008 sometime shortly after VS2008 ships. At the moment we don't have anything available."
According to Scott Guthrie:
"They [Web Deployment Projects] will definitely work with VS 2008 at somepoint - although I suspect we need to release a new rev of them that registers on VS 2008."
If you think Web Deployment Projects are important enough to be part of the final version of Visual Studio 2008 instead of being just an add-on you can vote for feature: "Include Web Deployment Projects in release of Visual Studio 2008" on Connect: