PostGIS ERROR: could not load library "/usr/lib/postgresql91/lib64/postgis-2.0.so"

Thanks to MikeToews I was able to fix this issue. PostGIS 2.0 in openSUSE depends on libproj0 and its version must be >=4.8. Somehow package manager didn't notify me about new version available for the libproj0 so I checked its newer version manually via Yast in "Versions" tab. After an update I'm able to operate database normally.