There are no doubts about it-- tablets have hit the WW notebook PC market hard. Further confirmation of this comes from a SplatF chart comparing notebook sales (the industry overall and HP) with Apple's.
Things were much brighter for the notebook market back in 2009, with notebook sales reaching growth totalling 20 - 40% Y-o-Y. Current notebook growth is now but a fraction of its former self, and is basically flat.
The notebook's fall coincides with the iPad's rise. Notebook growth for Q1 2011 is, well, 0%-- while Apple growth totals 53% Y-o-Y.
SplatF says while the iPad is making life difficult for the PC notebook, Apple's Macbook business is "still growing impressively". We'll see if that continues to be the case once Apple reveals its Q2 2011 (a full quarter of iPad 2 sales) totals next week.