Guy Creese's take
While Google Sites is a huge improvement over Page Creator--and Google is saying it's the last missing component--I'm not convinced that this latest incarnation will be enough to get large enterprises to buy Google Apps. Google Apps has been a big success with small and medium size businesses who want to avoid paying for an IT staff for as long as they can. But the Fortune 500 companies I talk to are still nervous about the lack of some nuts and bolts features, such as 24/7 phone support, the inability to administer the system via roles, the rudimentary e-mail distribution list capabilities, and the lack of records management capabilities for documents and spreadsheets. These are non-glitzy requirements, but real requirements nevertheless.
So while Google continues to improve Google Apps from a user interface point-of-view, it hasn't improved the underlying data model--Google Apps still shows its consumer heritage. (E-mail distribution lists that contain other distribution lists have been around for 20 years--yet Google has yet to include that important enterprise feature). While that isn't hurting Google within the SMB space, it is within the larger enterprise space. The vendor race in the collaboration and content space continues.