About a couple of years back, I wrote about how Google had a tight integration between its various services, and how Yahoo lacked it.

However when I made that entry, Google had very few services and Yahoo had lots of them. In fact, Google was primarily a search company and Gmail and Calendar were just new arrivals in the scene.

However now that Google has already been Yahoo 2.0, it's time to look at Google's offerings again and see how they have fared.

The first impression is that Google has done tremendously well. Although they have acquired several companies in the last couple of years, they have been very quick in integrating these applications with their portfolio. Orkut, Gmail/Gtalk integration, Gmail/Google docs integration, Google Mashup Editor are some examples.

However on second thoughts, it looks like there is a lot that is still to be done.

What kind of integration can we expect?

• You bookmark resources in various services
• Starring entries in Google Reader
• Starring posts in Google Groups
• Starring Google search results
• Noting down items or clipping entries in Google Notebook
• Indicating your favorite books in Google Books.

• Social network everywhere

• Presence awareness everywhere

• Uniform look and feel

• Attention profiling

It is a complex problem to solve. You don't know what the various interaction points between the various services are or what the various dimensions are for these applications. However, we learn some of these over time. For example, it looks like social networks and attention profiling are here to stay. So if you are building an application, ensure that it is integrated well with some social network and also takes into account the attention information of a user.