Adding to the growing buzz — some of which he helped create — around a possible refresh of Apple’s AAPL iMac line of desktop computers, Kaufman Bros.’ Shaw Wu issued a report to clients Monday morning with the latest update from his supply chain sources.

Noting that AppleInsider reported Friday that Apple seems to be running short of iMacs, Wu makes the following bullet points:

  • Timing: “In our experience, when AAPL sends an advisory to its channel partners of limited availability and inventory of existing models are drawn down, it is highly likely that a product refresh is within a few weeks.”
  • Specs: Wu is now hearing that the new iMacs will be available in both dual-core and quad-core models. “We believe this makes sense as this helps AAPL create better tiers within the iMac family, utilizing quad-core for the high-end, and dual-core for mid-range and low-end.”
  • Market share: Wu estimates that the iMac accounted for 25% of Apple’s Mac business last quarter (portables accounted for more than 70%) but could account for as much as 36% after a refresh.
  • Mac Pro: He believes Apple’s high-end tower, while less important than the iMac, is also likely to get updated. “We think a refresh utilizing upcoming Intel ‘Nehalem’ 8-core processors (and with two enabling a 16-core) would bring it better price performance and help jump start this highly profitable segment.”

Wu leaves himself considerable wiggle room in terms of timing. Even as he writes about an update within a few weeks, he quotes sources indicating that the iMac is “due for a refresh in the March or June quarters.”

The March quarter wraps up in eight weeks. The end of the June quarter is 20 weeks away.

See also: Why the iMac is late