No, images are not important for SEO, but if you do have them on your site, make sure to place alt tags for each image. These tags may include keywords, if relevant to the description of the image. Don't just stuff irrelevant keywords in though.
Wells sorry guys if I will disagree with you. I think images has an important part in SEO today. It should be wisely mixed with your text contents. A lot of site I know generate a lot of traffics from images on their site (through image search) and its a good source of traffic. If wisely used images can rock your SEO world. :)
Spiders only read text. so basically only content and keywords are important. Images are use for beautification and details so visitors will not be bored visiting the site.