Is there a decent and newbie-friendly group chat solution available?

Question

The problem: we want to move away from Skype for our group chats, but can't find a satisfying alternative.
What we do right now: we use group chats a lot, for various purposes, but mainly a) discussing certain topics, or b) planning activities/inviting people over, etc. People use all kinds of different operating systems.
Currently we use Skype for that. The advantage of Skype is its ease of use: users can create group chats by simply clicking on a few names. Chats are persistent: if you go online and come back the next day, you'll still be in the chat, and you will be able to read what was discussed in the meantime. If you add somebody to a chat, they are in it immediately, without having to enter a room address, or a password, or something like that. The participants of a chat control who gets added to it, and you cannot join a chat without being invited.
The disadvantage is its closedness, which makes us depend on a single vendor's client software and their monetary interests. Plus it has been bought by Microsoft, so the future of the already lagging development of the Linux version is unclear - and users of other OSes have been generally unhappy with the recent versions. Also users can not integrate Skype into already existing multi-protocol-messengers like Pidgin, they have to run the official Skype version at all times they want to chat at.
Quite a while ago a couple of us made an attempt to move our group chats to Jabber, but the acceptance was really low - opening a chat room was a hassle, they had to be password protected to be private, invitations weren't automatic, or the invitation features of clients were buggy, and by going offline you left a chat room, meaning people had to rejoin the next time they were online, and didn't automatically get to read the conversation that was held while they had been away. IRC is out of the question too, because it lags nearly all the features mentioned above.
Now I am wondering if anybody here knows about a free, open Chat software, that makes group chat (nearly) as easy as they are in Skype.

Answer 1

Well, IRC does not meet quite a few of our criteria. A typical chat lifecycle might look like this:
User A decides he wants to play football the next week. He starts a chat, adds 10 contacts that he knows might be interested, and makes a suggestion for a date and time. People come online, instantly see the chat and everything that has been written, answer, etc. Others join the chat later, see what has been said, and leave. Somebody might invite a couple of others to the chat, which will be immediately added. People play football, have a bit of postgame discussion, and then either plan the next session, or the chat dies.
I just do not see how this is a workflow that we can easily achieve with IRC - at least not in a way that people will be happy with.
- you can not automatically add people to a chat afaik
- chat history is not persistent afaik
- you do not necessarily want everybody to be able to just join a chat, but you also do not want to do a lot of configuration to restrict access to a chat/channel, when it might be about tonights event.
- people do not want to type /join #birthday_present_for_xyz, they just want to be added
I don't know why, but the openmeetings demo just doesn't really work for me - I get a lot of connection errors, it's painfully slow and hangs itself.