As a follower of trending for social networks and social media, i can say choosing one platform over another to clone is a bad idea. should you have interaction functionality? absolutely, but to have facebook intentions built into the core is a BIG FAT ScrewUP. if FB falls in the future, though not saying it will not saying it wont, but if it were to fall or the trend swing in another direction, then what kind of pain in the ass would it be to clean all that crap out of the code.

dont build this see more crap into dolphin. if its not required for core functionality, then set it modular. not everybody is a user of facebook, and not everybody wants to have to deal with issues which are related to facebook, such as jay mentioned, the updates on the fb api. that change unannounced.

dolphin should have its own profile, quit trying to perform as a facebook alternative, because its not about facebook in the social networking arena, not solely about facebook.

yes there should be a module for the following:

(and any other of the gazillion names you can think of, but these need to be modular, and not built into the core)

build dolphin, the core, get it debugged and functional, then you can add all the glitz and glamour that your heart desires, but keep the core of dolphin solid. modules changes, trends change, your core should update way less than your modular spectrum.
Facebook is as Facebook does and they do do everybody. That is their strength but it is also their weakness. At some point, it will get old and people will start moving back towards, smaller, more topic specific sites. Everyone has different interests in life. The best thing I think to do is figure out ways to cater to those specific interests and create sites that are interactive, safe and by the mere fact that every member likes rose colored Popsicles (or any other topic) makes them all brothers see more and sisters.

I know no one here believes me and many don't even understand what I am talking about most of the time but Facebook will be it's own worst enemy. For instance, the whole idea of having 'friends' was designed as a way to control the literally millions of people joining and using the site. What happens when the numbers begin to dwindle? The site will fail with the same exponentially increasing speed that it experienced in it's meteoric growth. If you have ten million users with 10 friends each and 5 million of them lose 5 friends well, you get my point. It's a house of cards.

I have been saying this for months and I'll say it again. The BEST thing Boonex could do with Version 8 is make the friends idea a mod that can be completely switched off. It will allow the smaller, more topic specific sites (that's everybody, except Facebook BTW) to gain and maintain it's community 'character' far earlier in the game thereby raising the percentage of how many sites are actually successful.
This isn't going to be in the core. As Andrew has already stated "Yes, there will be a Facebook module from BoonEx. We're trying to figure out how much is to be included."
Andrew Boon
For something to go into the Dolphin core it has be open-source, fully downloadable, independent and royalty-free. Facebook APIs won't ever qualify. Also we don't want to stick more than one brand to your bumper with default package that's for sure. So, yes, we are only talking about module, but trying to understand how much attention, if any, a BoonEx-made Facebook module should get.

As for the other in your list.. interesting topic on it's own:

skype - p2p system, specific application, more see more like "plugins" category

twitter - interesting phenomenon, "different" and straightforward approach, but possibly only one-fifth of what Dolphin is supposed to cover. There's a lot more moving space when you build for specific applications.

linkedIn - good one (although I find it a little messy for interaction) and we're looking at it routinely.

google - still largely a failure in anything social, although some other products provide a lot inspiration (Gmail, Android)

blogger - still going strong, but seem to be stagnating at what they're doing, no? We're watching them too, though.
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