So far, Apple's first fiscal quarter of 2010 is showing signs of becoming another record quarter with big year-over-year increases in Mac sales for October and November. The latest US sales data from market research firm NPD shows that Mac sales are up 21 percent for the first two months of the quarter, but that's not the end of the story.

Breaking out the sales data for notebooks and desktops shows a reversal of recent trends where growth came from sales of MacBooks and MacBook Pros. Sales of Apple's portable machines were only up five percent for October and November. However, sales of desktop Macs are up a whopping 74 percent. While revised Nehalem-based Mac Pros are likely moving just fine, chances are that big bump is likely related to the apparently huge demand for Apple's 27" iMac.

"While it remains early, it appears the new iMacs are driving Mac sales in the December quarter," said Piper Jaffray analyst Gene Munster in a research note, "and we are incrementally more confident in slight unit upside in the December quarter." An uptick in units would indeed be impressive, giving that the 3.05 million Macs that Apple sold last quarter was a record number for the computer maker.

Given the average selling price of Apple's computers and the healthy 30 percent average gross margins the company earns from each sale, Apple seems likely to top the record quarterly revenue ($10.2 billion) that the company pulled down in the fiscal first quarter of 2009. It would also continue Apple's tradition of posting record revenues in the holiday quarter.