There's a lot more than that meets the eye happening beneath the surface. When you have a thousand photos up there, you'll get a better feel of our algorithmic clustering.
There's at least some work by the algo to recognise different moments of the same day, I still need to upload more pictures to try to understand it correctly.
- I wouldn't want to sign up or upload any of my pictures before I know that I am going to actually use the site
It's free, you can try it if you really want. You can even use someone else's pictures. Asking for the algo seems too much.
First, it's important to know that uploading a thousand photos is way easier on such a site, since you do no organizing work. Try uploading a thousand photos to Flickr without culling, organizing into albums, tagging and captioning, and see what your result looks like. It doesn't have to be like that.
Second, they have to be your photos for you to appreciate chronological organization. When I look at my own, I can say, "Wow, I just click 2005, then December and I see my Puerto Rico pictures. And I didn't have to organize them myself." You don't get the same effect looking at someone else's.