while it's true from a storage standpoint that HDV makes sense, i still don't believe there's a use for it yet. there's no distribution method for HD get. blu-ray and hd-dvd will battle it out for some number of months. it'll be months/years before one wins and the average person has a player in their home. so basically, the gigantic bump is resolutoin really doesn't mean much unless you're upconverting to film... which most of us arent.
as Evan has backed up, the XL2 has 24p and is a fabulous camera. if you plan to make films to distribute on DVD and online, i recommend you get one, or the XL2, as an HDV camera does not help you at all when it comes to this. so get an SD camera, since DVD's are all SD anyway.
and, as i said on another post... in the event that you actually DO want to upconvert to film to project, i STILL wouldn't get this camera. if you have the money to upconvert to film, you have the money to buy a better camera. but otherwise, if you're just aiming for regular ole DVD, don't even bother with HDV... yet. wait for a format to be adopted, wait for consumers to buy the hardware, and wait for manufacturers to produce even better HD/HDV cameras for cheaper prices.