Piper Jaffray analyst Gene Munster is weighing in on the ultra-portable Mac rumours again. Munster is now believes that there is an 85-percent chance of Apple releasing the long-rumoured ultra-portable Mac at Macworld Conference and Expo in January 2008.

“As Macworld approaches, reports of an ultraportable MacBook are following patterns of previously expected products that eventually materialized,” analyst Gene Munster wrote in a note to clients. “We believe these reports are legitimate and continue to expect Apple to introduce a MacBook with a significantly smaller form factor.”

AppleInsider recently cited “well-respected” sources who, following nearly two years of internal development, Apple has finally declared the 13-inch sub-notebook ready for unveiling at the upcoming Macworld.

Gene Munster recently announced the ultra-portable Mac as his “Hot Topic of the Month.”