In a week of good results across the board, Apple’s (news, site) must be the most impressive driven by iPhone sales, which hit 18 million units worldwide for the quarter that closed at the end of March, and iPad sales, which if lower than some might have predicted, were nevertheless very impressive.

Overall, the company posted US $25 billion dollars in revenues, US$ 11.2 billion more than the same quarter last year, fueled primarily by record iPhone sales, very robust demand for the iPad and strong growth in Mac sales, according to Chief Financial Officer Peter Oppenheimer.

On all that, Apple made net profits of US$ 5.99 billion. In terms of the number of units sold, leaving aside the iPhone sales, it sold 3.76 million Macs during the quarter, an increase of 28% on the quarter last year, 9.02 million iPods, a decrease of 17% on last year, and 4.69 million iPads during the quarter. Apple did not however, breakdown the sales in those of iPad1 and iPad2.

iPad and Supply

For many, the question as to why iPad sales experienced a decline from the 7.33 million iPads the company sold during the fourth quarter holiday season has not been explained, but it seems to be more to do with supply issues rather than anything else.

According to Chief Operating Officer Tom Cook, speaking to analysts after the figures were released, Apple just can’t get iPad2 out the door fast enough.

Demand from the iPad2 has been staggering, and we have been amazed that we were still heavily backlogged until the end of the quarter," Cook said, adding that Apple faces "the mother of all backlogs" with the iPad 2.

For most that would be a good complaint, and although he did not clarify what the issues were other than extraordinary demand, he did note that the earthquake in Japan, where Apple sources a lot of its parts, had little or no effect in the last quarter. Apple did not experience any supply or cost impacts from the quake, he said.

That said, it seems that demand across the enterprise is the driver for supply issues around iPad 2. Peter Oppenheimer explained that at this stage, Apple is distributing in 59 countries with CIOs in corporate environments “embracing iPad at an unprecedented rate.”