Here you find the powershell script which were very useful for me.
All scripts are free of charge, use them at your own risk :
Hier is een methode om meerdere pst files in 1 maal in te laden in Exchange 2007.
Lokatie van de pst files: E:email Benodigdheden: Outlook
Read more... Powershell: Bulk import PST files in exchange 2007