Tomorrow, Microsoft and Yahoo are expected to announce an agreement which will connect their IM networks, which would allow users from one network communicate (including text and voice services) with users on the other. There has never before been a partnership between major competitors in the IM business to enable cross-network communication, which had led to third party clients to connect to many networks simultaneously, such as Trillian.  One possible reason a deal like this may not have been made sooner is because of all of the recent threats to the communications industry, including Skype and Google Talk.  The alliance between Yahoo and Microsoft will give them 44% of the market, and this deal will obviously put some new pressure on market leader AOL, which has 56% of the market. [via Digg]