I'm not all that familiar with Web Forms 2.0, but have been using xForms in relation to an XML-based project. A few of the benefits over traditional HTML forms (again, I don't know how they compare to Web Forms 2) are that they are device-independant (same form works on a handheld, smartphone, etc. as well as in a browser or desktop app) and the data you submit is XML-compliant.
I'm not all that familiar with Web Forms 2.0, but have been using xForms in relation to an XML-based project. A few of the benefits over traditional HTML forms (again, I don't know how they compare to Web Forms 2) are that they are device-independant (same form works on a handheld, smartphone, etc. as well as in a browser or desktop app) and the data you submit is XML-compliant.
The wc3 has a lot of good info about xForms:
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There's also an interactive tutorial:
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