You're going to get a lot more volatility on a day like today, but some of this activity, in combination with the Microsoft announcement, has clearly accelerated the volume on the day.
This is clearly a holiday-impacted trading day, as volume indicates. I do think the market is acting extremely well. The Christmas rally that people eagerly awaited is here, but it's taking on something of a more subtle tone.
But it's also a dangerous period. There isn't a lot of news and the volume is low, so the market is going to move more on rumor than on fact.