The auto software update feature tells me there's a new version of marsedit, "MarsEdit 1.1.7 (247) is now available. You are currently running 1.1.7 (245)." I downloaded the version from the update window and it still gives me this message. Also, the Software Update windows forces itself over all other windows that are open, should only be on top of it's own windows.
Upon download completion, you need to click the button that says "Install and Restart" or something similar. Most likely, the window just got behind of the other MarsEdit windows.
Hi Greg - yesterday brought so many troubles with the Blogger support that I ended up releasing 247 as a "1.1.7" as well. This is a little bit confusing, but I think in the end it will be better than racing through the 1.1.x numbers so quickly.
I think it's possible that Takaaki is right - that the window got stuck behind MarsEdit or something. Please try doing the update again, and then "Insall and Restart." It shouldn't ask again after that.