TL;DR: yes, but additional action may be required depending on the license. 

Check out this FAQ entry: http://opengameart.org/content/faq#q-proprietary It covers the "additional action" that may be required for each license pretty well. Nothing too scary; just stuff like "credit the author and share the stuff you make with it" is the most strenuous thing you'd have to do to comply with the license, but a lot of the specifics depend on the details of your project. If that doesn't clear up your question, please do not hesitate to ask for more clarification by replying here. :)

@JhinMan:  I have been working on revising the site docs and submission faqs to help clarify things around the licenses and answer questions such as yours.

If you go here:

http://opengameart.org/forumtopic/site-faqsubmission-guidelines-updatesc...

And wade through a bit of expository text, you'll find a brief run down of the various licenses supported and their terms of use.

Please note, the document is just a draft and you should definitely read through the whole thread if you are thinking of using CC-BY-SA or GPL works as there is quite a bit of further discussion of them in there.

^Yeah, actually capbro's post is more thourough and helpful than the FAQ link. I know I put a "TL;DR:" but in order to get a real answer to your question, you're going to have to do some reading.