[powrtoch]

Unless I'm mistaken, this is targeted at webmasters who want to use these features in their websites. I haven't downloaded/installed, but my guess is that it provides a workaround component that your page can link to. Similar to the existing javascript workarounds for transparent PNGs. The point is to improve the experience of IE6-8 users on your site, not for you to enhance your own IE installation.

But correct me if I'm wrong, like I said I'm just assuming.

[smitjel]

Yes, it's javascript overhead you have to add to your site so that people using IE will be able to see CSS3-like effects. So why add the overhead just so users of IE can have rounded boxes and gradients. Why bother? It's just eye candy...

[compay]

On many sites, IE 6-8 users account for more than half of visits, and are often the single largest block of visitors by browser. Assuming you have such a site and don't want to just write off 50% of your users design-wise, it's nice to have the ability to use border-radius and other CSS3 advances, because they save you from a lot of time-consuming, repetitive work.

If you are in a situation where you can simply forget about what your site looks like in IE, then I envy you. Most web designers are not.

[smitjel]

No, that strictly depends on how you've designed your site. To have your site look the best in ALL browsers, make subtle use of CSS3 effects. Don't _rely_ on them. If you follow that, you won't be writing off "50%" of your users design-wise.

[compay]

Sure, but then you're writing off CSS3 and continuing to write code as if it were 2006, which I personally don't like having to do.

[powrtoch]

Let's not forget conditional comments. The overhead for other browsers could be completely negligible.

[smitjel]

Excellent point.

lojjic, you should illustrate that in the docs somewhere.

[epe]

I don't believe it's any Javascript overhead for non-IE browsers. It's just a single line of CSS:

behavior: url(path/to/PIE.htc);

that non-IE browsers will simply ignore.