They're checking something in Hamiltons car:
From http://www.fia.com/germanygp/documents/GER_08_Race_Report.pdf
The engine of car number 22 is kept sealed in order to carry out further checks according to Article 5 of the
2008 FIA Formula One Technical Regulations. These checks will be done before the Hungarian GP.
From http://www.fia.com/germanygp/documents/GER_08_Race_Report.pdf