There is now a search widget installed in the sidebar. Look for the blue "blogbar." You need to click on the "this site" radio button and then select "Google Blog Search" in the bottom pull down menu if you want to search this blog site.
Posting Tip: Before you post do a quick search of the previous postings using the key words of your topic. That way you will know if anyone has already posted on that topic. You can certainly post on the same topic but you don't want to repeat the same ideas or quotes.