The actual date of leaving seems quite uncertain, though.
The "well informed" Brazilian fan site Technopop has reported such a decision repeatedly in 2008.
The music news site Resident Advisor confirmed Florian missing from stages back in April 23th 2008 at the opening of their Amercan tour.
Almost anyone else is reporting the leaving on January 7th 2009.
The official website of the group, as well as their current German label, EMI, is not reporting about it, while Elektrodaten, Kraftwerk's discussion community, is very laconic.
Curiously the English language Wikipedia chapter (among other languages) has been updated, while the German one looks still outdated.
Sadly enough, all good things come to an end."