  We present a new data set of transit observations of the TrES-2b exoplanet
taken in spring 2009, using the 1.2m Oskar-Luhning telescope (OLT) of Hamburg
Observatory and the 2.2m telescope at Calar Alto Observatory using BUSCA (Bonn
University Simultaneous CAmera). Both the new OLT data, taken with the same
instrumental setup as our data taken in 2008, as well as the simultaneously
recorded multicolor BUSCA data confirm the low inclination values reported
previously, and in fact suggest that the TrES-2b exoplanet has already passed
the first inclination threshold (i_min,1 = 83.417) and is not eclipsing the
full stellar surface any longer. Using the multi-band BUSCA data we demonstrate
that the multicolor light curves can be consistently fitted with a given set of
limb darkening coefficients without the need to adjust these coefficients, and
further, we can demonstrate that wavelength dependent stellar radius changes
must be small as expected from theory. Our new observations provide further
evidence for a change of the orbit inclination of the transiting extrasolar
planet TrES-2b reported previously. We examine in detail possible causes for
this inclination change and argue that the observed change should be
interpreted as nodal regression. While the assumption of an oblate host star
requires an unreasonably large second harmonic coefficient, the existence of a
third body in the form of an additional planet would provide a very natural
explanation for the observed secular orbit change. Given the lack of clearly
observed short-term variations of transit timing and our observed secular nodal
regression rate, we predict a period between approximately 50 and 100 days for
a putative perturbing planet of Jovian mass. Such an object should be
detectable with present-day radial velocity (RV) techniques.
