Learn Spanish (Latin America): El jefe nos lo acaba de anunciar.

The phrase acabar de followed by an infinitive (an unconjugated verb, like anunciar) is a special formula used to talk about the very recent past. Even though the English translation says something 'has just happened' in the past, you always conjugate acabar in the present tense here.

Why are the pronouns in the order nos lo instead of lo nos?

In Spanish, when you use two object pronouns together, the indirect object (who it is for, like nos) always goes before the direct object (the thing being acted upon, like lo). A common rule of thumb to remember this order is 'people before things'.

Since there is an infinitive (anunciar), can I attach nos lo to the end of it?

Yes! You can place the pronouns before the conjugated verb (nos lo acaba de...) or attach them directly to the end of the infinitive. The sentence could also be correctly written as El jefe acaba de anunciárnoslo. Notice that when you attach them, you must add an accent mark over the a to keep the spoken stress in the original place.

Does the verb acabar always mean 'to have just done something'?