I saw a comment earlier in the thread about wanting to have the same web project model in VS 2005 as in VS 2003 (single assembly, with a project file for definitions).
We are actually making this available via the VS 2005 Web Application Project Model option. A preview is available as a web download now at: http://webproject.scottgu.com.
A feature complete version will then be available later this month or the beginning of next month. We will also then add this to SP1 and support it going forward with VS in addition to the web-site option.