I'd second Heroku, it's awesome, though it is rather more elegant than most PHP developers may be used to.
Just tell Heroku about your Git repo, push, and it's live. Within certain limitations it's also free, you only pay when you start to scale, and this is done by dragging sliders. The downside is that the filesystem is read only, so if you're doing image uploads you have to store them in the database, which is actually really no big deal.
Brightbox is also great. You install a gem and it handles your deployment for you via Capistrano, so for me to deploy now I just type: cap deploy, wait 5 minutes while it uploads the zip, and it's live.