Yes they do. They aren't very effective but they do help.
I build a mixture of relevant and irrelevant links for my sites and i've been doing very well on the SERPs.
One thing that i've noticed is that irrelevant High
PR backlinks boost your rank on Bing 3x more than that on Google. Bing somehow lacks a relevancy testing algorithm which probably makes even irrelevant links from blog comments, etc.. look natural to it.