Microsoft Research has released a tool that analyze all the pictures in a folder, picks the "most interesting" ones and makes a blended collage. You can download a trial version at http://research.microsoft.com/AutoCollage/ that runs for 30 days, then you have to buy a license from the online store.
I have tried this tool for an hour and I think AutoCollage does a great job of creating a collage which can be used to share highlights from an event; wedding, vacation, weekend in Stockholm, etc. I don't primarily see these collages as something you print and put in an album (but perhaps it could be used as a cover page to an album), more probably it will be useful for digitally sharing your experience with friends and family. But perhaps printing them big and use as banners is one possible usage.
AutoCollage is a first release and may not have every feature you wish for but it does a good enough job for me.
Below is an example of a collage created using some images from my hobby (bird photography), an MS event and some private pictures. Note that AutoCollage takes into consideration the shapes of flower and makes an irregular crop. It also blends the lighter parts of the boys head and the wedding ring.