About the frontpage question:
"You and your friends went to a party. where do you put the photos? Right here!"
--- ehh wrong, personally I'd put my photos on facebook. I have an account there, my friends do as well, so I don't get it... sorry :S
If you want your photos on Facebook, divvyshot is the best way to get them there, as well as the best way for Facebook users to receive them, but I'm not sure how much of the functionality is in beta/secret.
If a group of you wants to put all the photos you took at some event in one place, where do you put them?
Dropbox?
Usually in a Flickr pool.
Facebook. You can tag your friends and they will be notified. That's a huge advantage, because not only the tagged person comes to see but also her nosy friends.
Sorry, I was unclear. By "one place" I meant one page, not one domain name.
Facebook without a doubt. It's what everyone does, and while it's slightly broken because all the albums for one event aren't linked, it's not a huge problem. It's something that would be nice for Facebook to fix, but isn't major. At least that's my opinion as a user.