http://forums.unrealircd.com/viewtopic.php?f=38&t=5789
You can still use the old watch, WATCH +name1 +name2 +name3, etc or you can use WATCH A +name1 +name2 +name3 and it will also show you when they go away, come back from away, etc.

Will mIRC support it?

"The board requires you to be registered and logged in to view this forum." <-- unreal's forum.

I imagine mIRC can already support this WATCH protocol inherently through its raw scripting support (assuming nothing wonky is going on with the spec). Whether or not mIRC will have some native UI for this is a different story-- that's less likely.

WATCH has been available on at least one other IRCd for a long time and I know it works there. It should work with Unreal as well.

He's talking about a specific and new variation of WATCH.