After some recent changes whenever I open a question the page title reads <first-question-tag>-<question title>-Stack Overflow
.
Tags are often quite long - for example there's visual-studio-2008
tag on SO. If browser uses tabs the tag might occupy all the tab width and no room for actual question title is left - this makes navigating between tabs inconvenient.
<title>
have more weight (for confirmation see Rebecca's link, above) so prepending is optimal.