Well it looks like i've bumped into a bug.
I know they brought back the create a Web Solution inside the New Project dialog throuhg SP1, but i'm getting the vibe, they just re-enabled it and didn't update the template files accordingly, because if you create it through the New Project dialog, the template generates the Page directives using CodeBehind attribute, which is depericated, while if you make it inside the Web Solution dialog, it generates the correct Attributes using CodeFile attribute.
Has anyone else experienced the same issue?