You can assign the hash table to a variable and pass the variable to the configuration parameter, as follows:

$TheData = @{
 AllNodes = @(
 @{
 NodeName = "server1"
 Roles = @('Foobar')
 ExampleSoftware = @{
 Name = "ExampleSoftware"
 ProductId = "{b652663b-867c-4d93-bc14-8ecb0b61cfb0}"
 SourcePath = "c:packages	hesoftware.msi"
 ConfigFile = "c:foo.txt"
 }
 },
 @{
 NodeName = "server2"
 }
 );
 NonNodeData = @{
 ConfigFileContents = (Get-Content "Config.xml")
 }
}
InstallExampleSoftware -ConfigurationData $TheData

You can also assign the hash table directly to the configuration function:

InstallExampleSoftware -ConfigurationData @{
 AllNodes = @(
 @{
 NodeName = "server1"
 Roles = @('Foobar')
 ExampleSoftware = @{
 Name = "ExampleSoftware"
 ProductId = "{b652663b-867c-4d93-bc14-8ecb0b61cfb0}"
 SourcePath = "c:packages	hesoftware.msi"
 ConfigFile = "c:foo.txt"
 }
 },
 @{
 NodeName = "server2"
 }
 );
 NonNodeData = @{
 ConfigFileContents = (Get-Content "Config.xml")
 }
}