If you go to the US website of Google play store to order Google Nexus HSPA+ than you can see the line written in the side of your shopping cart that this phone is upgradable to Android 4.1 Jelly Bean. This line definitely proves on fact that the upcoming Android 4.1 will be called Jelly Bean but initially it was rumoured that Android 5.0 will be called Jelly Bean.
Jelly Bean as from the design looks like a minor upgrade to ICS OS. The new design involves some changes to the wallpaper and to the Google search bar.