Do we need a dedicated Scrum Master?

The need for a full-time Scrum Master is often a topic of hot debate in many Agile projects. Based on the numerous agile projects that we have successfully executed, I would give the following recommendations -

• If your team is adopting SCRUM for the first time, then it is better to have a full-time Scrum Master. He would be responsible for ensuring that all agile processes are followed and everyone understands the rules of the game. The Scrum Master essentially acts as an evangelist educating teams on all aspects on SCRUM.
• Once the teams have become comfortable with SCRUM processes, then we can have a part-time Scrum Master. IMHO, the technical architect or tech lead is most suited to play this role.
• One of the main functions of a Scrum Master is to remove all impediments that the team faces. To be successful in this role, you need someone who can understand the technical complexities, business drivers and has a good rapport with the product owner. Hence architects are a good fit for the role of a Scrum Master. 
• The Scrum Master also facilitates the daily Scrum and weekly Scrum of Scrums to facilitate collaboration across teams. He also leads the retrospectives and facilitates combined learning.