My most recent job was with Intel. I got invited to some kind of recruiting event, I'm not sure how. One of my friends was trying to get me to join, so maybe he sent them my email address? Or maybe they spotted me on LinkedIn? I have no idea. Anyways, I ended up talking to one of their senior engineers on the project they were hiring for. I can't remember if it came out then or later that that senior engineer was a college friend of a guy that founded a startup I had previously worked for. Not sure if that made any difference or not, but I had relevant experience in the area they were hiring for, so they brought me in for an interview. (Which turned out to be an all-day ordeal, but I passed.)
The startup I had worked at before, I was hired because I went to a local un-conference, Portland BarCamp. I ran into someone I know from the Personal Telco Project, which started back in the early days of 802.11 wireless networking and was trying to promote free access points around town. Anyways, he knew someone else there that was hiring for a startup, so he introduced me and we talked and I went in for an interview and got the job.
In either case, it's not like friends are directly getting me jobs (as far as I know), it's more that my network of acquaintances aligned in a favorable way and I was in the right place at the right time.