1. -Web 2.0 innovations—from interactive widgets to distributed video to social networks—require new modes of Web analytics and measurement. 2. -The most accepted next-generation Web 2.0 metric today appears to be “engagement.” 3. -Engagement essentially measures the ways and degree to which users interact with an online ad. 4. -However, there is little agreement on precisely what engagement means. Web analytics analyst Eric Peterson is trying to define a complex engagement algorithm. Microsoft recently introduced a new Engagement Mapping metric and is testing it with national advertisers. 5. -Ultimately, any Web analytics metric needs to correlate back to marketing goals, such as lead generation or brand recognition, experts say.