During the same period, Dell's shipments grew 11.9%, from 4.697 million to 5.254 million. HP's shipments also grew, but only 5.6%, from 3.944 million to 4.166 million.
That gives Apple 8.5% of total PC shipments in 2Q 2008, says Gartner, compared to 31.9% for Dell and 25.3% for HP. Apple still has a long way to go, of course, but it's making progress: its market share of shipments in 2Q 2007 was 5.6%.
Gartner says that this data includes desktop PCs, notebook PCs and x86 servers. That last skews the data against Apple: although the company does sells its Xserve in small businesses, Dell and HP are giants in the server market.
It's safe to assume that if you're strictly talking about notebook and desktop PCs, Apple's share of shipments was significantly higher than the 8.5% mentioned above.