Diddly and I were talking about this on the weekend, so here is some of the information (and speculation) I've found regarding the iPhone 5, anticipated to be released later this year.  If you expect to be in the market for a new smartphone in the near future, it may be wise to read this before making any decisions!

First, CNET's list, updated regularly:
http://reviews.cnet.com/8301-19512_7-20073431-233/iphone-5-rumor-roundup/?tag=hotTopicsBody.1

I intended to post a link to a video I watched last week, showing the new iPhone chassis, which seems to have a slimmer profile, but a larger screen (maybe a centimeter or so longer).  The connector port seems to be smaller, the headphone jack seems to be on the bottom of the phone instead of the top, and there's speculation that the back will be removable so that camera lenses can be swapped.  Ufortunately, the video has now been marked as "Private".