With Apple’s new MobileMe Internet service launching Wednesday evening — and replacing its similar .Mac service — there’s a bit of trepidation in the air. What if MobileMe is as dorky as the name implies? What if Apple simply removes a .Mac feature and replaces it with … nothing? What might happen to posted iWeb pages and sites? To data stored on iDisk? And what’s this “Exchange for the rest of us” all about? Will it cost extra? Fortunately, MobileMe is more about increasing the functionality of the existing .Mac applications than it is about running roughshod over them.