Both Google and Donuts have applied for the .PLUS extension, and depending on who ends up administering the TLD, the use of this namespace will differ. If Google administers .PLUS, it will be used as an extension of Google + services, and offered to those who belong to the Google + personal and business networks. If Donuts administers the TLD, .PLUS will become an open registry, available to anyone, and might be perfect for companies offering perks, second-editions, or new features.
There is no specific procedure related to the registration of a domain name.
.plus domain names are allocated on a "first come, first served" basis.