I don't get excited about betas of games I'm already playing. In honor of full disclosure, I don't play betas to help the developers improve/test their game either. I play betas to get a free taste of what a new game is like. So the news of the alpha of Cataclysm being available doesn't feel me with giddiness.
I got in the beta of the Burning Crusade and I wish I hadn't participated. I know I will, after all, purchase expansions. Why see it in advance when I can savor the moment and see it for the first time once money has changed hands. It's not like they let you keep any progression you've made and carry it over to release.
I went to MMO champion and peeked at some of the Cata screenies and wish I hadn't done that as well. I don't need to be sold on Cataclysm, so I don't see what I could gain by immersing myself in all the Cataclysm news beforehand.
If there's one thing WoW does, is take their time releasing expansions. We get bored and start complaining about lack of content. Why burn out on the next one before its even begun?
Weekend minipost: Fresh start
14 hours ago