A weird driver appeared after upgrade to 15.04

In English this sounds something like this:

• Unknown: Unknown

  This device is not working

  • Using Processor microcode firmware for Intel CPUs from intel-microcode (proprietary)
  • Don't use this device

Someone could explain me what's this?

This is a new feature from 15.04 in ubuntu-driver-common. Ubuntu will now automatically try to find hardware and their additional drivers and packages to have a better more stable (hopefully) system with less user hassle. For example in 14.10 nvidia optimus GPU drivers had to be installed from a separate PPA but in 15.04 the system knows that they are there and they show up in additional drivers section.

As for what the microcode is:

The microcode data file contains the latest microcode definitions for all Intel processors. Intel releases microcode updates to correct processor behavior as documented in the respective processor specification updates. While the regular approach to getting this microcode update is via a BIOS upgrade, Intel realizes that this can be an administrative hassle. The Linux Operating System and VMware ESX products have a mechanism to update the microcode after booting.

From: https://downloadcenter.intel.com/download/14303/Linux-Processor-Microcode-Data-File

Which basically means that Ubuntu is getting driver updates (performance enhancements and bug fixes) from intel to make your system run better. So don't worry, it should be there and it is probably best to leave it as is.