Есть. Только что испробовал

. В синаптике добавил репозиторий natty:
deb http://archive.ubuntu.com/ubuntu natty main universe multiverse
Поиском выделил установленные пакеты clamav, у меня их 7...
Ctrl+A => Пакет => Указать версию => (natty) => Применить...
Было:
# freshclam
ClamAV update process started at Mon Mar 14 15:58:16 2011
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Local version: 0.96.5 Recommended version: 0.97
DON'T PANIC! Read http://www.clamav.net/support/faq
main.cvd is up to date (version: 53, sigs: 846214, f-level: 53, builder: sven)
daily.cld is up to date (version: 12833, sigs: 72570, f-level: 60, builder: edwin)
bytecode.cvd is up to date (version: 142, sigs: 40, f-level: 60, builder: acab)
Стало:
# freshclam
LibClamAV Warning: zlib version at runtime is older than compile time: 1.2.3.3 < 1.2.3.4
LibClamAV info: Make sure zlib is built as shared library, and that the new zlib library is installed in the proper place
ClamAV update process started at Mon Mar 14 15:59:44 2011
main.cvd is up to date (version: 53, sigs: 846214, f-level: 53, builder: sven)
daily.cld is up to date (version: 12833, sigs: 72570, f-level: 60, builder: edwin)
bytecode.cvd is up to date (version: 142, sigs: 40, f-level: 60, builder: acab)

Ага, ругается на библиотеку zlib... Проделываю вышесказанное и с zlib... Обновилось 2 пакета...
Вот что получилось:
# freshclam
ClamAV update process started at Mon Mar 14 16:05:47 2011
main.cvd is up to date (version: 53, sigs: 846214, f-level: 53, builder: sven)
daily.cld is up to date (version: 12833, sigs: 72570, f-level: 60, builder: edwin)
bytecode.cvd is up to date (version: 142, sigs: 40, f-level: 60, builder: acab)

Вроде получилось.
Ну и на последок не забыть бы отключить репозиторий natty...