The Disney construction is far from Marriott's Ko Olina Beach Club. If you have an ocean view villa, you will probably be able to see four tall cranes beyond the Centex Beach Villas at Ko Olina, but there is no disruption at Marriott's Ko Olina Beach Club.
A bigger issue at Marriott's Ko Olina Beach Club is that interior construction of the incomplete half of Hale Nai'a (building 3) is likely to resume some time in 2010. It could be disruptive if you have a room in the completed half of Hale Nai'a.
If you have an ocean view room at the JW Marriott Ihilani, you should also be fine. However, the Disney site is directly across the street from the JW Marriott Ihilani, so some non-ocean view rooms face directly toward the construction site.
We stayed at Marriott's Ko Olina Beach Club the last two weeks of July. It's a great property. We enjoyed walking to the JW Marriott Ihilani and dining there.
I posted two articles with recent photos:
http://www.yesterland.com/disneykoolina5.html
http://www.yesterland.com/disneykoolina6.html
The second article above has links to a whole series of articles about the Disney resort at Ko Olina.