Although it has not yet been announced, investment bank Piper Jaffray believes it's only a matter of time before Apple reveals plans to hold a special event next month to usher in a new array of iPods and Mac notebooks.

The Cupertino-based company has used a September gathering to launch new iPods for the past three years, analyst Gene Munster advised clients in a research report Wednesday, adding that Apple shares have risen about 4 percent on average from the week before those events to the week after.

Historically, shares have risen more than 47 percent between the week before those events to the four months after, he said.

At this year's event, Munster is expecting Apple to refresh its iPod family through a number of "pricing and capacity changes." Specifically, he's looking for capacity increases to iPod shuffles and iPod nanos, but no price reductions on those models. Conversely, the iPod touch is likely to see a redesign "and a new $199 price point, in line with the iPhone."

Sharing the stage with new iPods will be a complete overhaul of the company's mainstream notebook families, Munster believes. In particular, the analyst sees Apple unveiling new industrial designs for both the MacBook and MacBook Pro, and possibly re-entering the $999 price point on the MacBook as it once offered alongside the notebook's iBook predecessor.

"We note that the MacBook has had the same design since its launch over two years ago, and the MacBook Pro has had essentially the same design since its launch over 2.5 years ago, which was very similar in design to the PowerBook G4 released over 5.5 years ago," he told clients. "To compare, the long-running iMac G5 design lasted three years."

In his note to clients, the Piper Jaffray analyst also weighed in with his thoughts on how Apple will expand the presence of its multi-touch technology on the Mac going forward. He said gestures recently added to the MacBook Air and MacBook Pro "are just the beginning of Apple's exploration of multi-touch on the Mac," and that the company clearly holds plans to leverage its technology portfolio from the iPhone to simultaneously advance Mac experience.

"Currently, these gestures require the same touch-sensing technology used in the iPhone, but they use a traditional looking trackpad," the analyst told clients. "Eventually, we expect Apple to change the trackpad to backlit color screens for a more dynamic user interface on the Mac."

Ultimately, Munster expects Apple to introduce a full touch-screen MacBook, although "not until the technology has fully matured over the next 2-3 years."