We are not planning to support embedded text formatting like IRC, Jabber etc. In fact we automatically remove all that, because that conflicts with our idea of styled interfaces which gives you the unique and spectacular chance of having an actually good-looking chat experience by any designer's rulebook.
Technically, PSYC is a text-based protocol. It can be compacted and it can carry binary data in body and variables, but its outer structure still intentionally has a text-based syntax. A few bytes more (really) that make application development easier, for instance by allowing us to create messages simply by filling out a template rather than needing a dedicated renderer.