I'm watching on an iPhone 4.
The thumbnails are rotated 90 for me (wrong), but the pictures are fine.
I suspect there is macro data imbedded in the picture, describing its orientation.
...and my phone corrects the view.
Looking via working Windows computer....
Yea, thumbnails off by 90, and so are pictures when I view them in their own tab (Firefox 22.0).
edit: Windows XP Pro
Dan - just shoot your pix in landscape instead of portrait mode, and see if everyone is happy.
You might shoot in portrait, then load 'em into an editor for cropping, but that sounds like WORK!
(if they show up in your editor, rotated...you probably will have a Rotate button to fix 'em)
.