For all of you bloggers out there that like embedding gists but are frustrated by the lack of line numbers, I found a nice CSS solution.  After a little googling, I found this solution by potch.  It looks as though the structure of an embedded gist has changed slightly so I modified the css to look like the following:

.gist .highlight {
    border-left: 3ex solid #eee;
    position: relative;
}
 
.gist .highlight pre {
    counter-reset: linenumbers;
}
 
.gist .highlight pre div:before {
    color: #aaa;
    content: counter(linenumbers);
    counter-increment: linenumbers;
    left: -3ex;
    position: absolute;
    text-align: right;
    width: 2.5ex;
}

Include this somewhere in your stylesheets and viola, you get nice line numbers for all of your embedded gists (in modern browsers at least).