From an amateur photographer point of view: Microsoft Live Photo Gallery
I'm an amateur in photography. It's my hobby, maybe even a passion. I have my own gallery on Flickr which people see from time to time to enjoy those few frames I've put there.
Some time ago I watched a video presenting how Live Photo Gallery can be used to put photos together and stich them into panorama. Warning: it's a marketing video.
After this short presentation and actually having some photos from my trip to Portugal I've decided to compare a tool I've already been using for some time, PTGui with the new baby from Microsoft.
Here is a result of stiching in PTgui:

And here is a result from Window Live Photo Gallery:

It's pretty amazing that tool which can be downloaded for free can do something as cool as a few $$ software!
The results are not entirely the same. Live Photo made the picture a bit flatter than PTGui and didn't give me any options to correct that. This is why right side as well as the left side of the photo is climbing towards the centre of the frame. OK, it's not ideal but it's hardly recognizable!
That was my one and only test I made with Photo Gallery but I have to say, I'm quite impressed with its results. I'll have to start making more panorama photos.