Now that Microsoft's first Real-Time Communications (RTC) Server (code-named Greenwich) beta release is out the door, the company is prepping a series of upgrades to its Instant Messaging (IM) clients that complement the company's RTC Server plans. Microsoft will issue new versions of MSN Messenger and Windows Messenger in the coming weeks, according to sources close to the company. In related news, Microsoft released a new version of MSN Messenger for Mac OS X yesterday that includes features none of the product's Windows counterparts yet have.

Due soon from Microsoft are MSN Messenger 6, the company's consumer-oriented IM client, and Windows Messenger 5, which targets enterprises. The Windows Messenger 5 beta is available as part of the Greenwich beta and includes simultaneous support for three IM services: the Internet-based Microsoft .NET Passport, SIP Communications Service (Greenwich), and Microsoft Exchange IM. Also new in this release is support for the Tablet PC's digital ink format, which lets users send ink email messages, including handwritten text and drawings. Users who don't own Tablet PCs can choose to receive digital ink messages from users with Tablet PCs; if this feature is turned off, the Tablet PC user sees a new Ink entry form so that messages are converted automatically to plain text for the other user. One feature missing from Windows Messenger 5 is Hotmail integration: Instead, Windows Messenger launches Microsoft Outlook when new email arrives.

MSN Messenger 6 and Windows Messenger 5 will both reportedly offer IM archiving capabilities so that users can save conversations automatically or manually. Yesterday, inexplicably, Microsoft made this feature available first to Mac OS X users in the MSN Messenger for Mac OS X 3.5 client. This release also supports other small changes, including performance improvements and new graphical flourishes.

Greenwich, which is due this summer, will be a Windows Server 2003 add-on that provides corporate-ready IM features built on the Session Initiation Protocol (SIP) technology that first debuted with Windows Messenger in Windows XP. Since that time, the company's RTC plans have shifted dramatically. Microsoft originally slated corporate IM as a feature of Exchange, the company's messaging server, but with the move to SIP, Microsoft decided to include the technology as part of Windows 2003. In mid-2002, however, the company detached the RTC Server from Windows 2003, citing diverging development paths. Greenwich will now ship 3 or 4 months later than Windows 2003, and Microsoft has been mum about licensing plans.