Well I hate to oversimplfy a fix for this problem (I am a Win7 user and all of my apps/viewers/mail and my recipients viewers show my photos upside down).
With the introduction of using the Volume + button, I take most of my photos in a landscape orientation similar to a regular digital camera. But like most of you they are all upside down.
I simply take photos now with the iPhone oriented with the Vol+ button at the bottom of the phone, not the top as Apple designed and advertised the feature.
All of my photos on the phone are visible in the right orientation.
All of my emailed or text'd photos from the phone come in to recipients in the right orientation.
All of my photos in Windows Office Picture Manager, Adobe Photoshop, Paint, whatever views it..... are correct.
Cheesy? You bet. But this is a stupid issue and very much an Apple viewer compatiblity support problem. Please do not push purist views as it relates to the EXIF spec.
This is a consumer product that needs to perform properly with mainstream applications. Apple is notorious for throwing their customers under the bus in order to make an industry statement that 'we are right, everyone else is wrong'. Case and point = FLASH support. Say no more.
I design software. Good companies test their solutions to ensure they are widely compatible with most mainstream customer applications. Arrogant and spoiled companies would much rather sacrafice their customer experience in order to posture and dictate how other software companies must comply.
This issue can only make Apple look bad. Most find it hard to believe that every other application they use is wrong and Apple is pure and right.
I say fix the problem Apple and show us you listen.