Please read USCIS' March27 news release

USCIS will begin accepting H-1B petitions subject to the fiscal year 2008 (FY08) H-1B cap on Monday, April 2, 2007. USCIS will not reject cases delivered during the weekend (March 31 or April 1). Instead, USCIS will treat those petitions as if they arrived on April 2. The deciding factor for USCIS is when the agency takes possession on the petition and not when the petition was postmarked.
This announcement is related to the deliveries made on Saturday and Sunday, any delivery to the agency on Friday will face rejection.

One more thing: The filing tips ask to use blue color pens to sign the forms.