Rumor site, 9to5Mac.com, reports that Apple will unleash the iPhone/iPod touch SDK on February 26th. The site also claims that Exchange and Lotus notes support will be announced as applications.
They also speculate that new MacBook Pros equipped with Penryn chips and 10.5.2 will also be released on that day.
If a special event does pan out, Mac|Life will bring you live coverage of Steve unleashing new products to the masses.