Continental Airlines ended their participation in Membership Rewards last September. United has never participated. You can transfer your points to another Star Alliance program and redeem for travel on any Star Alliance airline including UA.
Generally, you should not transfer until you are ready to redeem and should compare the miles and fees for the same trip redeemed through ANA and Aeroplan. ANA's program is distance based, while Aeroplan is a zone system, similar to UA's.
Additional discussion here:
http://www.flyertalk.com/forum/ameri...ntinental.html