I'm curious how this will play out, I don't know how the Dutch legal system works anyone fill us in on the system and how this judgment fits into it? It would appear that it is only a judgment that he can be prosecuted not that he will be prosecuted?
I'd be glad to

. No, the decision is that he now
must be prosecuted.
Even before Fitna, a lot of individuals (and institutions like Muslim federations, I guess) have filed complaints about Wilders' various comments with the police and the public prosecutor. It is then in the power of the prosecutor to decide whether he will prosecute a complaint or not. As a rule, the prosecutor will make such a decision within a reasonable time (6 weeks or so), and inform complainant of it. In this case, I gather that the prosecutor dragged his feet to even make the decision to prosecute or not. About a year ago, just before Fitna, there was a TV show around lawyer Gerard Spong (mentioned in the linked BBC article), where a member of the audience identified himself as one of the complainants and mentioned this. Upon that, Spong promised him to help him with the case.
So, in the end the public prosecutor decided not to prosecute.
In that case, according to article 12 of the Dutch Law on Criminal Court Proceedings, interested parties (e.g., complainants) have the option to file a request with the Appeals Court to overturn the decision of the prosecutor. So, what such a request asks is that the Appeals Court instruct the public prosecution to prosecute a case - before a normal court.
A number of the complainants against Wilders have filed such a request with the Amsterdam Appeals Court, and the news item is about the decision of the Appeals Court. From what I've heard on radio and TV, the decision is quite lengthy - 35 pages - and involves not only hate speech charges but several related charges. The bits and pieces I heard recited gave the impression that the Appeals Court, between the lines, in fact already gave a damning verdict on Wilders' comments.
ETA: From what I heard, the Appeals Court considered complaints about Fitna as well as complaints about various earlier comments from Wilders.
However, it is not up to the Appeals Court now to give a verdict. The public prosecutor has to bring the real case before a normal Court; then it'll undoubtedly will go to into appeal before an Appeals Court, whoever wins the case (*), and after that even to the Dutch Supreme Court and the ECHR, as I heard a law professor muse on radio.
(*) obviously Wilders when he loses. But the prosecution also now has the strong moral obligation to pursue the case with all its might. Article 12 decisions in favour of the complaining parties are very rare, only a couple percent of the cases IIRC. So this Appeals Court decision already is a big win for the complainants.
Reactions from political parties have been mixed. The major coalition parties PvdA (Labour) and CDA (Christian-democrat) just said "it's up to the judge". SP (Socialist Party) and VVD (right-wing liberal) regretted it, saying they think discussing with Wilders belongs in the political arena, not the legal arena.
ETA: Wilders, of course, thought the decision ludicrous. He added that he enjoys immunity for everything he says in Parliament, and he could have refrained from making the same statements outside Parliament, but he hadn't done so because that would be hypocritical. He has a good point there.
There is (scarce) legal precedent for prosecuting MPs. Some 20 years ago, Janmaat was successfully prosecuted for anti-foreigner remarks that seem very lame in today's context. Some 10 years ago, fundie-protestant MP Van Dijke was prosecuted for disparaging statements about gays.