I'm glad I'm not a Canon lawyer. Keeping straight the questions of excommunication, schism, valid vs. invalid, licit vs. illicit, formal schism vs. informal schism, and faculties is a complicated matter.
So, two posts from Fr. John Zuhlsdorf here to help explain things. First, the SSPX is not, technically, in schism; however its bishops and priests are under latae sententiae excommunication, and are therefore considered suspended. Masses said by the SSPX are valid, however; a Catholic may attend an SSPX Mass without incurring a canonical penalty or committing a sin. While Masses are valid, in that the priests are suspended, they may not hear confessions or perform marriage ceremonies. This is from Cardinal Castrillon Hoyos in a letter to Brian Mershon, who inquired, and seems to be the most definitive statement from the Vatican on how the church views the situation. On a second matter, while the SSPX has technically met the deadline for the Vatican's response (despite some indications that they were not going to), they do not yet give full assent to all of the Vatican's points, some of which they consider vague. They have countered with a request that the Vatican remove the excommunications before they proceed further. I'm thinking that's unlikely, but Cardinal Castrillon Hoyos was reportedly pleased with the response, as far as it went.
It's at some level fascinating -- I won't go so far as to say it's like watching spiders mate -- but I think that at some point, this dance has to end. Either the SSPX and the Vatican restore full ties, bringing 1 million Catholics back into full communion, or they walk apart. I think there is a great temptation for the SSPX to walk apart, to say "hey, we've got a valid Eucharist and apostolic succession, let's go it on our own" but I think that is a very foolish and prideful path. I think the Pope and Cardinal Hoyos have gone a long way to try to resolve the dispute; I wish the SSPX would show some ability to reconcile. To me, their answers seem too grudging and lawyerly. Better to come back in, first, and we'll resolve the other issues later.