Rob Howard may not be familiar with the Community Platform, but it is definitely not Community Server, which only runs MSDN blogs.

After a successful (but ultimately limiting) seven year experience with a proprietary and very closed community platform, we knew we needed something open and extensible.

Drupal fit the bill in almost all respects and the RainCity team tweaked it to our specific community needs. We’re now a few months afloat with the Drupal system and our users have picked it up swimmingly.

We’re now building a rev.2 wish list based on feedback from our hosts and members. Thankfully, we can dig in to the guts of Drupal and change what needs changing for our community. Our hands aren’t tied on specific developers, companies, or approaches.

Don’t worry, Boris! RainCity is still in our hearts and minds… but it’s nice to have that option! It’s also a good selling point when you are pitching open source apps in your enterprise.

Every platform will have at least one pitfall, so finding one that is both flexible and open is the key. If that pitfall becomes a crevasse over time, an open system will allow you to pick up your data and move on.

MSDN is running Community Server (http://communityserver.org) by Telligent.

Community Server also powers the MySpace.com forums (http://forums.myspace.com)

Lastly I read that you mentioned OpenID support. Our newest version, Community Server 2008, has OpenID support built in natively.

It’s almost overkill while they still have a small base, but will be interesting to watch as it scales.

The tough part with many systems — especially closed, hosted ones — is that they provide great initial starting points, but then often lack in customization or growth options. And god forbid that your platform provider “go away” — then you’re completely stuck, and need to start over.

This is why I have chosen to go with fully open systems, because they can grow with communities and can never be locked down or disappear.

@Varun:
Facebook is ultimately closed and not a participant in the “open web”. And it’s someone else’s platform with someone else’s rules. I would hope that we steer around such closed instances and strive to connect openly.

@Peter Childs:
“What I’d like to see is a platform that recognizes communities are networks of interests (people & organizations) and doesn’t try to become a destination”

I think this is spot on — don’t try and a become a destination IN AND OF ITSELF — but rather add value through various aggregation and hub features. This also seems to argue for mini-networks that cross sites.