According to Weekly Shounen Sunday magazine vol.50, an OVA of "Hayate the Combat Butler" will be released as the episode 0 of the second season. The detail of the OVA will be announced soon.

Source: Scan of Weekly Shounen Sunday magazine

Edited on Dec 6th================
According to NewType magazine, the staff of Hayate OVA are as follows:

Director: Iwasaki Yoshiaki ("Wagaya no Oinari-sama.")
Series organizer: Kuroda Yousuke ("Mobile Suit Gundam 00")
Script writer: Sato Hiromu (episode script of "Zoids Fuzors")
Character designer: Fujii Masahiro ("Zero no Tsukaima")
Production company: J.C. Staff

The OVA will be released in the spring 2009.

Note: The production company of the first season was SynergySP.

Source: Scan of NewType magazine

Edited on Dec 19th============
According to Getchu.com, the OVA will be released on March 6th, 2009.

Normal Edition DVD 5,250 yen
Limited Edition DVD 6,090 yen
Normal Edition Blu-ray 6,300 yen
Limited Edition Blu-ray 7,140 yen
Source: Getchu.com