There are unconfirmed reports from DigitalPoint Forums that Microsoft is going to upgrade adCenter soon to support daily budgeting.
Currently, I believe, adCenter only has a way to set a budget at the month level. You can supposedly set a "daily limit" but that will pause your campaigns based on the monthly average.
This new feature should give advertisers more granular control over their campaign finances.
Forum discussion at DigitalPoint Forums.

Comments:
Charles Thrasher
10/12/2007 12:05 pm
AdCenter does have an equivalent of Google's daily limit, a feature that attempts to evenly distribute a campaign's monthy budget across each day of the month. My experience has been that it's somewhat uneven in practice. There is always the possibility that the entire budget may be spent before the end of the month or the campaign go into "budget pause" for no obvious reason.
Lancelot Trimm
08/15/2008 07:39 am
The Google Ad has moved the aspect of present marketing trend. It has brought revelution in the Internet Marketing sector.Has also opened up Job oppertunities for the comming generation.