MacroSchema

  
Even for people who have used .NET for years, studying for and attaining a certification will teach them quite a bit that they didn't know. Although I always think certifications don't directly reflect one's software design and implementation ability, nevertheless, it helps to "Keep your skills relevant, applicable, and competitive." - Microsoft

• 11/2009: Microsoft Certified Professional Developer(MCPD): Enterprise Application Developer - the Microsoft top-level certification for advanced developers
• 09/2009: Microsoft Certified Technology Specialist (MCTS) for .NET Framework 2.0 Web Applications
• 09/2009: Microsoft Certified Technology Specialist (MCTS) for .NET Framework 2.0 Windows Applications
• 02/2009: Microsoft Certified Solution Developer (MCSD) for .Net - the Microsoft top-level certification for advanced developers
• 02/2009: Microsoft Certified Technology Specialist (MCTS) for SQL Server 2005
• 07/2008: Microsoft Certified Application Developer (MCAD) for .Net
• 12/2007: Microsoft Certified Professional (MCP)

From this page from Microsoft you can find the numbers of certifications issued worldwide.