Bom, mas já que incomodei os senhores, tentei instalar o Mendeley pelo apt, inserindo a linha
Ign http://www.mendeley.com/repositories/Debian_5.0/ Translation-pt_BR
Hit http://security.debian.org squeeze/updates Release
Get:6 http://www.mendeley.com Release [1609 B]
Ign http://www.mendeley.com Release
Hit http://security.debian.org squeeze/updates/main amd64 Packages
Hit http://security.debian.org squeeze/updates/contrib amd64 Packages
Get:7 http://www.mendeley.com Packages [1611 B]
42% [7 Packages bzip2 0] [Waiting for headers] 535 B/s 12sbzip2: (stdin) is not a bzip2 file.
Err http://www.mendeley.com Packages
Sub-process /bin/bzip2 returned an error code (2)
...
W: GPG error: http://www.mendeley.com Release: The following signatures were invalid: NODATA 1 NODATA 2
Gerson.