Well seems like a time for celebration. With such worded messages from UKBA it's pretty sure that the visa is indeed on it's way.

Yes, even on the forum we have seen decisions being made as fast as 1 day for settlement visa's.
Others have suffered anxious waits of weeks.
Don't know exactly why other than an uncomplicated well presented "standard" application is much easier for caseworkers and ECO's to tick their boxes

Let us know when your wife actually holds the passport and visa