So far we've been very comfortable managing projects that have similar technical characteristics with our past projects. For instance we choose to get involved in python-based web application development because we have some Ruby and Java web based application on our hands. It is definitely easier compared to tackling an ERP implementation, because we haven't done an ERP implementation before.
However, we have to admit that getting our heads around the different problem domain in Python is a bit different compare to Java or Ruby. In our project we are working under the assumption (which 90% of the time holds) that the organization provides a team lead/architect who has enough experience in building the application and the ability to set the technical foundation upon which the team to work. The team lead/architect acts as our deputy to translate the technical jargon or concepts from the developer to the PM team.
We do note that this arrangement is often far from perfect. Technology develops in a pace with which no one person can cope. We often do our own networking exercise, getting acquainted with experts inside or outside the project/company who we can ask for help if we stumble across a problem in our project that our own people can't solve.
We just want to know of any other techniques that other PMs in this community use to bridge knowledge gaps within the team they they are leading.