Generally every wordpress blog adds a line in the head section of the Html source code which states that the page has been generated by wordpress x.x.x. The information about wordpress and its current version number is very easily visible in the head section of any wordpress blog. This does not cause any harm however, it provides some useful information for the nasty people. I personally feel that the information should bot be visible in the head section.
The information in head section looks something like this
<meta name="generator" content="WordPress 2.8.4" />
Removing that line from the head part of blog is quite easy. simply add
into your themes function.php file and it will be gone forever. If the generator line is still there, you can also check head section present in header.php file for the generator meta tage and remove it from there. Save the file and referesh you blog and hurrray its gone for ever.