I noticed that in 24p mode, the HD250's default shutter is 1/48th. The HD100 I've been using for the last year had a default of 1/24th. If I'm shooting walk-and-talk type standups and ENG style feature stories, what should my default shutter be? I mainly shoot in DV24P.

It should be 1/48th for 'normal' looking 24P footage. The 1/24th default in DV 24P mode is a mistake. Canon did the same thing on the XL2.

which ever looks good to you, and the people paying you money... that said, 1/48 is the traditional speed, but 1/24 can be a nice alternative in low light instead of kicking up the gain