Does it matter (for SEO, or any other reason) if the <h1> tag is not the first thing on a page?

I've seen some pages where the logo (image, no text) was in <h1> tags, so I assume it's because they wanted it to be the first thing before any other tags, etc.

For the page I'm working on now, there's a long sentence/short paragraph (intro) that seems to me to be the obvious <h1>, but it would come after the logo, main nav and a slideshow.

Would it be best to put the logo in <h1> tags (with alt text and title) and use <h2> for that intro text, or make the intro text the <h1>?

I'd say use the h1 for the logo and h2 for the intro. In html5 you can use h1 more than once on a page, as the heading for a section e.g.

Thanks, good to know!
I never would have thought of using an <h1> tag for an image, and couldn't find anything about it in my various "how-to" books.