<p>I've been looking for this information for my commercial desktop product, with no avail.</p>

<p>Specifically, what I'm look for, is deployment statistics of the .NET framework for end-users (both granny "I'm just browsing the internet" XP, and high-end users, if possible), and in the commercial/business sector.</p>

<p>Edit: Other than the data points below, here's an interesting blog post about .NET <a href="http://www.nbdtech.com/blog/archive/2009/05/25/what-percentage-of-users-have-the-.net-framework-installed-and.aspx" rel="nofollow noreferrer">deployment rates</a>.</p>

I don't have any hard numbers, but these days, it is pretty safe to assume most Windows XP and Vista users have at least .NET 2.0. I believe this was actually dropped via Windows Update for XP, and Vista came with at least 2.0 (apparently with 3.0 as pointed out in the comments to this answer).