Be sure to register for Trunk.ly - you'll see the landing page and the actual site are a little different, the logo will be used on both.
Trunk.ly has different connotations to different people, the original thought behind the name was "Elephants" as in "Never forget a link", however in practice the stronger association is now with a Trunk as in storage trunk.
Users commonly use this term "putting that link in my Trunk" for example on blogs or in conversation.
The goal is to come up with something that fits the current site design and that we can use across our branding (business cards, T-shirts and the website).
Longer term we'd love to see a character logo (like GitHub, Reddit etc.) and see how they can be used, however it's perhaps a little premature as the positioning of the site may change - if you're game we'd love to see some ideas but unless it was exceptional we're just as liable to pick a text based one because that's a safer decision until we are ready to invest more in the full branding.
We are targeting a broad internet user base, although most users at the moment would tend to be more technically savvy and male, it's not the end goal.
Other things that are important to us and differentiators are the idea of Search which is a really key component of our offering and where we are investing to improve it and Social.