Apple will hold a music-related event on Wednesday, September 1st. New iPods will be introduced, as it happens yearly. There is strong evidence of a new iPod nano based around the 3×3 cm touch screen seen earlier this year, and possibly a new iPod Touch with 3G data capabilities — essentially a smaller iPad. This leads me to think that these new units may require iOS 4.1 at minimum, and the new firmware could therefore be made available to iPhones (and older generations of iPod Touches — ok now that’s a weird plural) on the same day. Of course, the new units may be shipped with a particular version that won’t be made available to other devices, as it was with the iPad: iPhone OS 3.2 was never made available for iPhones, and iPads won’t see iOS 4 until the fall. Apple may also release iOS 4 for iPad on…