Images rotate in GR, but not rotated when uploaded

1.4.1 on WinXP.

And yes, I've read the FAQ... jpegtran, convert, and jhead are all in the path on my host (Linux host, and I control the host). One interesting thing to note (and this is kinda hard to explain)...

I went into the folder where the images I had just uploaded were stored locally. I copied jpegtran.exe from GR to that folder. I then ran jpegtran with different rotate values (outputting to a new file to preserve the original file between runs) and got interesting results

First off, these photos were taken with a Canon S1 IS which DOES have a rotation sensor, and I have the option in GR to auto-rotate on, but it doesn't happen (I also have it on in Gallery too... is that the cause of the problem?)

Original image is <-, which was rotated in GR before upload 90 degrees clockwise. It appeared in Gallery <-.

-rotate 90 makes the resulting photo -> (!!!)
-rotate 180 makes the resulting photo V
-rotate 270 makes the resulting photo <- (!!! same as original photo)

So, the photo is somewhat rotated, but both Gallery AND Irfanview (my image viewer) seem to think it's still oriented normally, but when I run jpegtran on it it seems to rotate as if it were oriented ^.