Microsoft's Mac Business Unit has released Messenger for Mac 5.1 and a significant update for Office.

The free updates are available for download from Microsoft's Mac website or using the AutoUpdate feature of the suite.

This follows the Macworld Expo San Francisco appearance of Microsoft's chief executive for Mac development, Roz Ho, where she promised significant Mac product updates this month.

Ho and Apple CEO Steve Jobs also confirmed a new five-year deal between the two companies, which formalises Microsoft's Mac support.

"We'll keep working with Apple, just as we have for more than 20 years, to meet the needs of all Mac customers," she explained.

The free 57.3MB Office for Mac update (11.2.3) focuses on Entourage, which is now indexable by Spotlight and supports Apple's Sync Services. Entourage also offers enhanced Smart Card technology that supports Keychain.

Entourage's support for Sync Services enables customers to sync calendar events, contacts and tasks with handheld devices and other applications that support Apple's Sync Services.

Used in conjunction with Microsoft's Live Communications Server, Messenger for Mac 5.1 can now encrypt chat sessions and file transfers. IT administrators also gain more control over saving chats at an organisational level.