Hendy Irawan has put up a great post on how you can sign Symbian/Qt Apps on the fly on Linux (Ubuntu) OS. With the latest version of Qt Creator 2.0+ (included in Nokia Qt SDK) you can now easily sign Qt/Symbian applications (.SIS files) with your Symbian Signed certificate and key files. The best part of it is that it can also be used with Linux operating systems (e.g. Ubuntu).

The Process is as follows:

To build a Qt/Symbian application on Linux and also sign the generated SIS file with your developer certificate and key, first you must install the Nokia Qt SDK Remote Compiler.

Open your Qt/Symbian project, go to Projects facet and add “Remote compiler” configuration.

Under Build Steps, expand “Compile at Server” details and you will see Sis Type and Symbian Signing settings.

There you only need to specify certificate file, certificate key file, and password/passphrase (if any).

As a bonus, you can not only sign the SIS file, but also automatically package it with Nokia Smart Installer!
Therefore, your Qt and Qt Mobility application now complies with Ovi Publish requirements and can be published to the Nokia Ovi Store!