I work for a small electronics company and am wondering if building a group page on LinkedIn would help our search engine optimization? When someone joins your group, does the link to your site on their page help increase your number of inbound links?

There are some social networks which will help your PR because they have not made the links on their sites nofollow. Linked In Q&A articles, Yahoo Answers and You Tube frequently show up in Google's SERP's so it is worth the time to develop company profiles on Linked In and You Tube. Facebook is questionable depending on your target demographic. Though most of the popular social networking sites won't help you with SEO to your site, they could rank themselves in the top 10 results, driving traffic and increasing your shelf space, so not a waste of time to use them.