The actual opinion won't be released until June. What Dude heard was a reporter stating they believed, based on the comments made by the individual justices during oral argument, that the court will find for gun owners.
Keep in mind, the court may declare that the 2nd amendment means individuals have a right to own firearms but that there are reasonable restrictions, just as there are with the clauses of the 1st amendment. That being said, they may decide the DC gun ban isn't reasonable. The problem then, of course, is that judges all across the country will have to apply the "reasonable" test to every case that comes before them. What is reasonable to me may not be reasonable to the next guy.
Lastly, the inner workings of the court is very political. From the assignments on who writes the decision to lobbying and bartering of votes, nothing is definite until the opionion is released. And even then, it may only muck up things even more.
"Whatever you are, be a good one."
- Abraham Lincoln