- Open source;
- Cross-platform (at least Windows, Linux, OS X);
- Text chatting, group chatting;
- Encryption of messages;
- Reliable eventual delivery of messages (including to offline contacts);
- Sending files;
- Skype-grade NAT traversal; bonus for IPv6 support;
- Sent messages editing;
- Searching in active chat and in chat history.
What can be used instead of proprietary Skype for text chatting?
Are there planned or alpha projects that explicitly (i.e. not like optional XEPs in XMPP) plan to do all the points above?
XMPP does all of the above well in theory, but not in practice (according to my experiments with various clients) and gives "design by community" feeling …