2007Q3: 8.1%
2007Q4: 6.1%
2008Q1: 6.6%
I call that a drop.
As briefly mentioned in the article, Apple's third quarter market share typically sees a boost due to the back-to-school bump and their popularity in that market. And quarter-to-quarter variations are also seen due to the timing of product introductions and refreshes. Here are Gartner's quarter-by-quarter U.S. market share numbers for Apple going back a bit further:
1Q08: 6.6%
4Q07: 6.1%
3Q07: 8.1%
2Q07: <5.5%
1Q07: 5.2%
4Q06: 5.1%
3Q06: 6.2%
2Q06: 4.6%
1Q06: 4.0%