In recent times, using the logo as a link back to the homepage has become the default way of handling the issue. Web designers use this method without thinking about it much, because everyone does it. They wrap the A element around the IMG element, and that does the trick. Maybe, but maybe not. While I think the method itself isn’t necessarily bad, using it does raise some usability questions.
A user who browses the web often, like yourself maybe, might instinctively go for the logo believing it is a link, but you have to assume others aren’t familiar with this method. An experienced web user has probably grown accustomed to it, but we’re building websites for everyone out there, not just the internet junkie. Users who aren’t aware the logo links back to the homepage might get confused when they search for a way back, which we want to avoid. Even if the user knows the logo could be a link, there might be better soultions to the problem.
We want to ensure the best possible usability on our websites, not just for the sake of the less experienced user, but everyone, so it’s a good idea to offer an alternative. Adding a simple text link “Back to the homepage” (or similar) somewhere in the header, is certainly an improvement. By doing this, we make sure all users are able to find the way back, quickly and avoiding any confusion. Now, even if the logo stays neglected or unexplored, there’s the text link that will do the job perfectly. The power of CSS is there, so you can additionally style the link, making sure it will be easily spotted.
The homepage itself of course does not need the “back home” link, which will confuse the user even more, so be sure to omit it.