FaceTime has a nice product out that can do just that. With Forefront for OCS not due out until who knows when it looks like one other company is rushing to fill the void.
"FaceTime Enterprise Edition provides organizations with the tools to standardize their Instant Messaging (IM) infrastructure on the Office Communications Server 2007 unified communications (UC) platform while ensuring compliance and securing their environment against IM-borne malware and spam over IM."
- Standardization on Office Communications Server 2007 by blocking access to unauthorized IM and P2P networks
- Built in support for both Microsoft Office Live Communications Server 2005 and Office Communications Server 2007
allows for flexible migration
- Identity management with policy control at global, group and individual employee levels
- Guaranteed TrueCompliance™ to meet corporate policies and government regulations
- Interoperability with existing anti-virus solutions
- Zero-day blocking of IM-based worm and virus attacks
- Anti-SpIM controls protect bandwidth and close security holes
- Archival of file transfers over Office Communications Server 2007 into WORM storage
- Advanced content filtering and keyword blocking to prevent loss of confidential information
- High availability and load-balancing deployment increases security and reliability of existing real-time communications infrastructure
- Targeted remediation and inoculation of spy are-infected endpoints without deploying client software
- Automatic protection against threats identified by FaceTime Security Labs