Linden Lab Official:Using Linden Lab's trademarks and logos
From Second Life Wiki
For information on using Linden Lab's trademarks properly, see:
For information on using the inSL™ community logo that you can use to promote your contributions to the Second Life world, see the inSL™ community logo.
To learn how to request permission to use Linden Lab trademarks in a way not allowed under the policy, see the trademark FAQ. If you still have questions pertaining to the use of our trademarks, send an email to firstname.lastname@example.org. Linden Lab can't guarantee a prompt response to every the email. If your question is urgent, contact a trademark attorney.