Today two different sources are claiming that Leopard will be delayed. DigiTimes reason that this is to enhance Vista support in Leopard and that it will not ship until October. To me this seems like an unlikely prospect, especially Vista has been out in Beta long enough (I think) for Apple to strengthen its Windows compatibility. Besides, Vista has been reported compatible with the current version of Boot Camp, which leaves little for Apple to improve upon, except for the odd Vista driver.
Ars Technica's Infinite Loop however are claiming a shorter delay, to June. And while this isn't exactly a delay from Apple's original Spring promise, most of us were hoping for an earlier release. While it makes sense to release Leopard at WWDC which is taking place in mid-June, I think that that there will be too much going on in one month if Leopard is releases then. That's because in June the iPhone is supposed to ship, as well as some possible Mac upgrades (which will hopefully also happen between June and now), which may be too much to talk about in one keynote. I also think it would benefit Apple's stock price to spread out product announcements rather than to group them all together (although if Leopard is not finished there's nothing they can do).
All we can do now is hope; hope that Steve realizes that he's making us write about Vista for lack of Apple news and turns on the Real Time Distorter inside Apple.