Actually it wouldn't

Here's how:
In AdminCP go to User Profile Fields > Add New User Profile Field > single lined text box and
Title: Myspace Profile
Description:
http://www.myspace.com/username <--- replace with your myspace username
Leave the rest and click on Save at the bottom. Note the field number when you are done (i.e. field5).
Now add it as a condition to your postbit like this:
find something like:
Add this after:
Code:
<if condition="$post['field5']"><a target="_blank" href="http://www.myspace.com/$post[field5]">
<img border="0" src="http://www.yoursite.com/images/myspace.jpg" alt="View myspace profile"></a>
</if>
Remember to change field5 to whatever the field number is that you've setup. This will only show for users that have it filled out in their profile. Also, here is the image that I used for this