At times one would really feel no need of the Quick Launch section on few pages or sites i.e. the Team Site, one would really love to use the full width of the page for this one. Luckily the Content Editor Web Part trick which worked in SharePoint 2007 still works in 2010.

To hide the Quick Launch
1. Add a new Content Editor webpart. (Doesn’t matter where you add it)
2. Edit the HTML Source for the newly added Content Editor Webpart

3. In the HTML Source add the following and Click OK.
#s4-leftpanel{
display:none
}
.s4-ca{
margin-left:0px
}
[Do not forget to add the style open and close tag as seen in below image due to rendering issues its not showing up]

4. Save the Page. The Quick Launch section should not be visible now.
5. Edit the Just added Content Editor web Part and Under Layout Section Tick the Hidden Check box and Click OK, Which will hide the Webpart from Normal View.

6. This works on any SharePoint 2010 or Foundation 2010 Page and site.

For MOSS 2007:
Add below code in content editor web part source editor.