I saw this thread and was like "yeah that's been bothering me, isn't there some way to do that?"
Let's face it, Skydrive is kind of lame when it comes to sharing pics. Then I realized: imgur! Sure enough, there's a great imgur app for WP8 called Grin - and it's free with no ads, even:
Grin is the best Imgur app for Windows Phone 8 | Windows Phone Central
I just tried it out and it works wonderfully. Just set it up, go to your camera roll (outside the app) and choose Share, choose Grin in the list, upload the pic (or pics, you can do multiple), and then it will give you a direct link to the full-res (5MP) image with a handy button to copy that link to the clipboard. The default link goes to the imgur page but you can also get links (from the app) that go directly to the full-res image. Here are some examples that I just uploaded:
National Archives - Imgur
http://i.imgur.com/EJLICXT.jpg
DC metro - Imgur
http://i.imgur.com/K1aRCj1.jpg
Aerogel - Imgur
http://i.imgur.com/SQ61Kc4.jpg
Some crazy piano - Imgur
http://i.imgur.com/4jKcB5A.jpg
Note that two of these are less than 5MP because I zoomed and/or cropped the image on the phone. So much for lossless zoom I guess.
Also note that imgur will recompress the images to have a smaller file size, but it keeps them at their original resolution. It seems to do a very good job of doing this without noticeably hurting the quality. So if you want the absolute highest quality this isn't going to do it for you, but if you just want to share the image at its original (5MP) res, it works great.