I consider using PowerShell or for that matter VBScript or Perl when I need to pull data from many SQL Servers, or need to implement a scriptable/repeatable solution (which excludes a GUI solution) or when I need to accomplish a task which would either be difficult or impossible to do in T-SQL. SQL Server Management Studio (SSMS) does not scale when you are working with hundreds of servers.

But, the main reason I started the SQLPSX project was to solve a problem of reporting on the security information for hundreds of databases across many servers. The solution needed to pull the security data into a reporting database and recursively enumerate roles and AD groups. This would have been impossible to do in SSMS or T-SQL, but easily accomplished in PowerShell.