On 11 February 2005 the European servers for WoW launched and the Shattered Ravens were founded. Yep, the guild I'm in is five years old today.
We've moved servers since then (we were on Argent Dawn for the first 11 months before moving to Steamwheedle Cartel-EU to escape the lag) and seen expansions take us to Outland and the Northrend. Friends have come and gone over the years, and while I don't recall how many of the initial characters are still active (Andromache didn't come along for a few weeks I don't think, but my palatank Buliwyf was a day-1 character, as I believe was Leafshine), but we're still here and doing our own thing - not always successfully, but having fun nonetheless.
We've seen guild drama and loot drama, and had spectacular loot drops. We've killed raid bosses, and wiped repeatedly. Friendships have been made (and broken). We've laughed ourselves horse, and cried bitter tears.
And we're still here, a wary eye on Icecrown Citadel and it's evil overlord while working our way through Ulduar while heeding the signs of the imminent Cataclysm. We may never face Arthas directly (our numbers are too few and our focus is more on fun than achievement which rather hampers raid progression) but we've played our part in this war.
Will we be here another five years? Who knows? The next expansion will bring sweeping changes to the game and it remains to be seen if that encourages people to play or prompts them to depart. What I am sure of is that I've yet to see an MMO that has the same depth and breadth as WOW, nor the same level of fun.