Users of both IM apps able to exchange messages, conduct computer-to-computer voice calling Microsoft and Yahoo are expected to announce Wednesday that they will make their instant messaging software compatible with one another, allowing users of both to exchange messages and conduct computer-to-computer voice calling.The Wall Street Journal and other media outlets reported Tuesday an announcement was pending, citing anonymous sources close to the companies. Meanwhile, on Wednesday, the two companies said a press conference is scheduled for 11 a.m. EDT.Now, users of Microsoft’s MSN Messenger and Yahoo’s Messenger can’t send each other messages, but the expected change would allow that to happen, according to reports. Officials at the companies declined to comment prior to the scheduled announcement. Software DevelopmentSmall and Medium Business