Today I decided to update Blender to the latest version 2.70 from 2.68 I was using and bam! Was lucky to find a bug with textures in the first project I worked using the latest release, so after trying 2.69 and finding the same problem I reverted back to 2.68 and problem solved.
The issue I'm talking about is that texture layout parameters are not preserved on all faces of an object when exporting to Collada. Let's supose you open with Blender a Collada file that already has texture layout setup on all the object faces, like a privacy screen with tree panes. The moment I join those 3 panes and save the updated object to Collada, only one of those panes will show the texture right after I try to apply the textures in Second Life. And I have tried all possible Collada export options related to textures and coud not solve this issue.
Only going back to Blender 2.68 got me working again in the right path. Glad I could spot this bummer bug early on!