Jupchur,
The statement "HP servers" can now mean either servers from the NetServer line or Compaq ProLiant servers absorbed from the merger of HP and Compaq.
I assume you probably mean the first. There are currently no direct plans to test NetServer products for Unity support. The new, post-merger HP has publicly announced that the Compaq ProLiant server line will transition to supercede the NetServer as HP's IA-32 server solution. See the following URL for the announcement:
http://www.hp.com/hpinfo/newsroom/press/07may02b.htm
As for ProLiant, Cisco Unity supports a wide range of ProLiant servers already: DL320G1, DL380G2, ML370G2, DL580G1 and ML570G1
Additional HP ProLiant servers will be supported given customer solution needs.
Regards,
Victor
Cisco