From Froum.Nokia...

The "Designed for S60 Devices" logo program is set up for developer use in application marketing. The program features an S60 logo specifically designed for developer use, with the aim of making it easier for developers to communicate that a particular offering is designed for S60 devices. Enrolling in the logo program enables you to:

Associate your offering with the leading smartphone platform, S60.
Demonstrate that your offering is designed for the S60 platform.
Take advantage of marketing momentum built up by S60 device manufacturers.

Enrolling in the program and obtaining rights to use the logo for eligible software and applications must be done through the program registration system which gives access to the S60 Feature Brand Guidelines, accompanying S60 Trademark License Agreement, and the logo materials. The legal terms and conditions for using the logo for eligible software and applications is explained in the S60 Trademark License Agreement, available through the registration system. Please note that any use of the logo requires valid registration and acceptance of the S60 Trademark License Agreement. To be entitled to associate your offering with the "Designed for S60 Devices" logo, you must at all times remain fully in compliance with the S60 Feature Brand Guidelines and the terms and conditions of the S60 Trademark License Agreement. Any breach of the program requirements defined in said agreement and guidelines will result in the termination of your right to use the "Designed for S60 Devices" logo. (Source: Forum Nokia)

For more information and to register, see "Designed for S60 Devices" Logo program