The largest number of Apple's computer sales was iPads, which are quite a seasonal product. But since their numbers are growing year over year as well, the pattern is record sales in the fourth quarter, less in the first quarter of the year, and then going up again with higher record sales in the fourth quarter. So you can expect Apple to be #1 again about from the 3rd quarter this year and then permanently.
Sales numbers are of interest for two reasons: To find out what is going on in the business, and for bragging rights. For finding out what is going on, I'd like numbers separated; I'd like to know how many Minis, iMacs, Mac Pros, MacBooks, MBAs and iPads Apple sells, all separately. For bragging rights, which is what this article was clearly about, counting iPads is definitely right, just as netbooks that are much cheaper and less powerful than an iPad are counted as well.