TheMadScientist - 6:50 pm on Feb 28, 2010 (gmt 0)

I'm wondering about this since part of the category is anchor text and part is not:

In thinking about it a bit more I would only use it on the anchor text. You've already defined the surrounding information and the class="url" IMO is to let machine readers know where the URL for more information is.

You could also have this:
<div class="hproduct">
<div class="category">
<a href="page.html">Red</a> <a href="/another-page.html">Widgets</a>
</div>
</div>

To define which URL is more information for the product and which is the general overview page you would use class="url" on the product link and not on the other URL.

The question for me is, how will Google use hproduct in the future? It seems they want to break up a site's data into well-defined portions for display on their own site.

Me too... and on some sites, this is totally okay with me and others it's not, so how and where and what site I use hProduct on will be based on whether I want to allow them to show the product on their site or not.

For example, on a product detail page, should alt image text be used on the photos of items that are displayed for cross-selling purposes? That alt image text doesn't speak about the main theme of the page, which is the detailed product.

I don't do everything for search engines... IMO, and my way of doing things, (mostly) yes, because most sites I build are also accessible to screen readers because I think it's a good way of doing things, so if there are other products on a page I use the alt, but as far as Search Engines go, I try to keep everything well related, so SEO helps me keep things 'organized', which means the alt text on all images helps both.

IMO People who would say you should not use the alt on a site where IMO it should be accessible to screen readers are really, IMO, building sites for search engines rather than people. I don't make all the sites I work on 100% accessible to screen readers, but they're all now very close, mainly because I think it's cool to do for people who are a bit less fortunate... There was one I didn't make accessible from the start, but have since recoded most of it.

That only opens up possibilities for a whole lot of mis-classifications.

Doesn't it have to be surrounded in an hProduct 'div' according to the spec?
[google.com...]

In the first line, class="hproduct" indicates that the HTML enclosed in the <div> describes a product

IMO No hProduct = You can use whatever class you feel like, because you haven't defined anything as an hProduct, so I'm thinking there shouldn't be an issue.