As Web 2.0 could mean chaos determined by consumers disseminating content without limits, an Intranet will need some form of control over users and content, therefore will be somewhat Web 1.5 - 1.75.

Sharepoint gives the right balance of user control (with security, policies, logging, auditing etc etc), business processes (workflow), but also allows users to create new sites, subsites and content(docs, wiki, blogs) so to create no impediment. Therefore I believe the way to Web 2.0 for Sharepoint 2007 it is one of "software configuration" rather the software capabilities.