I think that pedrocr is from Portugal so in case you're learning Brazilian Portuguese you should consider that Brazilians usually use "estar + present participle" where the Portuguese use "estar a + infinitive" (for example "estou a falar" vs. "estou falando").
Brazilians thus have "estar sendo" which can be used in many cases where English has "is being", but as a non-native speaker I'm not sure what I can claim about its connotations or whether it's the same as "estar a ser". But my initial guess is that the Portuguese say "estou a ser" just as they say "estou a falar", while Brazilians say "estou sendo" just as they say "estou falando".
Spanish-speakers in turn have "estar siendo" with the Spanish present participle of ser, like "estoy siendo". I suspect this is the standard form of this construction in all kinds of Spanish.
Yep, that's exactly it. "is being" and "estar a ser"/"estar sendo" are pretty much the same thing. What english doesn't have is the "ser"/"estar" distinction, both map to "to be".
Thank you for the explanation. This clarifies why I haven't (consciously) seen the "estou a + infinitive" form yet - the Spanish and Brazilian Portuguese forms look more familiar to me. :-)
Brazilians thus have "estar sendo" which can be used in many cases where English has "is being", but as a non-native speaker I'm not sure what I can claim about its connotations or whether it's the same as "estar a ser". But my initial guess is that the Portuguese say "estou a ser" just as they say "estou a falar", while Brazilians say "estou sendo" just as they say "estou falando".
Spanish-speakers in turn have "estar siendo" with the Spanish present participle of ser, like "estoy siendo". I suspect this is the standard form of this construction in all kinds of Spanish.