I know this topic is a little old, but it's worth responding to.
I'm a little surprised at some of the obnoxious responses here. Because it's a phone and not a tablet? Shouldn't the
user determine whether or not they want the home screen to rotate? We're not iPhone users here.
I use
Set Orientation to solve this, but it's not a perfect solution. I set it to "auto," and then, no matter what program you're in, it'll let you change the orientation. That's why I say it's not a perfect solution; if I open "Zenonia" while my phone is in portait mode, it'll look weird.
I need this for my home screen because I use Handcent with popup text messages, and I like to type my responses in landscape mode. I came to Nexus 4 from Cyanogenmod, which allows rotation (I think because it uses ADW Launcher, or something like that). I got used to it, so I didn't want to lose it.
This program is also handy for other things. Google Reader doesn't have an option to force in portrait mode, so I use Set Orientation to do it for me. Otherwise, if I put my phone down for a minute, it switches to landscape and I lose my place. I installed it on my Nexus 7, too. Also, Set Orientation is free, which is why I made a point to post it here, because the programs listed already aren't free.