The proc passes the @RunID parameter to the package, as well as other usual suspects, such as the package name, folder name and project name. You can also choose if a package is run synchronously or asynchronously. When run synchronously, the stored procedure doesn’t finish until the package is finished as well.
Using this stored procedure, it is easy to run a package multiple times in a row using a WHILE loop.
Also of interest is Andy Leonard’s SSIS Performance site, whose goal is to set up some performance benchmarks for Integration Services.