These two webapps have been introduced after the OS went in "feature freeze"
Even though Ubuntu 12.10 (Quantal Quetzal) is now in feature freeze, meaning that adding new stuff has stopped for this cycle, an exception has been made for two new webapps, Amazon and Ubuntu One Music.Ubuntu WebApps enable developers to make web applications that run in Internet browsers. There are already a large number of them integrated into the system by default.
Following a feature request on Launchpad for “Installing Amazon and Ubuntu One Music Store webapp items in the launcher by default,” the guys from Canonical have made the decision to implement Amazon and Ubuntu One Music after the distribution went into feature freeze.
"Those two items (linking to the Amazon and UbuntuOne Music WebApps) would be added by default to the Launcher with the appropriate icons, distributed as part of each WebApp package,", said Alexandre Abreu, a software developer at Canonical.