For Office, there will be three MCTS level certifications for developers, each requiring 1 exam. MCTS is Microsoft Certified Technology Specialist, which is the technology-series certification in the new format of certification. There is also a Microsoft Certified Professional Developer (MCPD) series that focused on job roles... but we won't have any MCPD for office. I think the betas for these three are scheduled for January (more on betas).

MCTS: Office SharePoint Services (MOSS): Application Development (70-542)

MCTS: Windows SharePoint Services: Application Development (70-541)

MCTS: Office 2007 Client: Application Development (70-543)

More on the new certifcation format here: official overview: http://www.microsoft.com/learning/mcp/newgen/default.mspx or here: from one of my friends/co-workers at MSL for interesting take: http://vishaljoshi.blogspot.com/2005/12/are-next-gen-certs-launched-to-make.html