  We discuss the impact of the present-day uncertainties in the recently
released CHAMP and/or GRACE Earth gravity models on the measurement of the
Lense-Thirring effect with the nodes of the LAGEOS satellites. Also the role of
the secular variations Jdots of the even zonal harmonics is quantitatively
assessed via numerical simulations and tests. While the systematic error due to
the static part of the geopotential ranges from 4% (EIGEN-GRACE02S) to 9%
(GGM02S), the impact of the Jdots amounts to 13% over 11 years. This yields a
19% 1-sigma total error in the test recently performed with EIGEN-GRACE02S.
