GameDaily is reporting that the Silicon Knights v. Epic case is moving ahead after Epic's motion to dismiss has been denied. While they have mentioned this is "common," they haven't actually explained what it means. A motion to dismiss is essentially a motion to determine that the case isn't one for which there is a remedy at law even if the facts are true as stated. In this case, it would be the basic equivalent of Epic saying that Silicon Knights hasn't made any actual legal claims in their case. The judge, by denying this claim, is simply saying that he believes there is a claim or at least there is the appearance of a claim that can be remedied by law. The reason that it is common for motions to dismiss to be denied is that there is rarely something presented that is so outlandish that it makes no resemblance to a claim that can be remedied at law. If you would like an example of a time when a motion to dismiss would be appropriate, I would direct you to this lawsuit against Michael Vick.
The motion to dismiss is not to be confused with a motion for summary judgment, which is basically asking for a ruling without a trial in favor of one party. Put as simply as possible, if Epic had moved for summary judgment, they would stating that even if the facts are viewed in the manner most favorable to Silicon Knights, Epic would still be victorious in its claim. Motions for summary judgment generally occur after discovery, so they could still occur in this case. There is also a motion for a directed verdict, which would come after the plaintiff presents its case and essentially says the plaintiff has not proven their case. To use the continuing example, after Silicon Knights rests their case, Epic could move for a directed verdict on the basis that Silicon Knights has not sufficiently met the burden of proof necessary for their claims.
In sum, the Silicon Knights v. Epic case is moving forward at this time. Law of the Game will being more commentary as more developments occur. If you would like to read more about these motions, or about other motions, please visit this Wikipedia article.