What is the name of this green spikey plant (pic included)?

Question

http://thumbs.dreamstime.com/thumb_66/11503719730HtVwE.jpg

Answer 1

Hard to tell but it looks like it could be Hawaiian Silver sword.

Answer 2

Could it be Yucca rostrata (beaked yucca)?

http://en.wikipedia.org/wiki/Yucca_rostr...

http://www.ces.ncsu.edu/depts/hort/consu...

Sapphire Skies cultivar:

http://www.terranovanurseries.com/wholes...