OMFG - at last there’s a decent public Jabber service - with chat sync “as in skype”!
Technically, it means
Message Archive Management (XEP-0313),
Message Carbons (XEP-0280) and message delivery to offline enabled for users! All public Jabber servers I know disable it, so that your conversation history always gets fucked up, having messages lost and split across your multiple client instances.
Why would anyone need these promoted fenced proprietary messengers, which are unclear about your security and privacy (or, perhaps, clear about lack of it). Get armed with any decent standard Jabber client featuring standard encryption technologies, and get privacy-traders and adversaries suck a good time!
P. S. Terribly sorry for indecent language, I’m just that much excited about decency of this new service.