I don't pretend to understand this, but reading the paper this morning an announcement is expected tomorrow apparently. The speculation is that this will be announcing that the confidence level in the evidence they have been able to observe has been upped.
The confidence level is currently sigma 2 (about a 1 in 20 chance that the results that indicate the presence of the Higgs boson were produced by chance). The threshold that they have set for 'proof' is sigma 5 (about a 1 in 1.7 million chance). They may announce sigma 3 or sigma 4 tomorrow, the big news would be a sigma 5.
Apparently, Professor Higgs has been invited to the announcement, so that's fuelling speculation that it's a major breakthrough.
My favourite part of the story (in The Times today) was the final sentence. The announcement is being made on the eve of an international physics conference in Melbourne, "Australian scientists complain that not only would an announcement of the Higgs scoop the conference but, more importantly, it could clash with their opening drinks reception"
Wouldn't want the discovery of the 'God particle' messing up a perfectly good drinking session now, would we?