I'm David Jeske, the ex-Google acquiree who served as technical architect and engineering director for orkut.com (among other projects) from shortly after the Brazil popularity explosion through the service decline.

I have a few key points to add to this discussion (to the best of my recollection):

1. orkut.com was not acquired. It was developed in-house, the initial version almost entirely written by Orkut Büyükkökten as a 20% time project. It was written in C# .NET as that was what he was most familiar with and efficient in. The actual product launch was championed internally by Marissa Mayer, and encouraged as an experiement in-part because of the external pressure for Google to do "something" in social networking.

2. We believe a huge part of why it became popular in Brazil, was becuase the homepage contained a ranking of users by country and Brazil's national competitive spirit. Brazil made up the largest initial seed network, and once they were #1 on the leaderboards, it became a major viral spread factor in Brazil to "stay on top" of the leaderboard. It was unfortuantly much later in the service that we realized a good portion of why it remained popular only in Brazil was because the service tended to surface the largest sources of activity to users, which meant most users saw significant amounts of Portuguese content. Once we segtregated the service by language, we saw it experience it's second cultural explosion in India.

3. Once we kept up with performance demand on the service, orkut.com fairly quickly grew to serve more daily pages than Google.com websearch (though obviously it was much less complicated as a service, and much less profitable!) However, over time the service became increasingly dominated by abusive usage such as adult images and fake user spamming. orkut.com was always a very small team within Google, as I recall at it's height we had only around 8 engineers on the project as this was very far from Google's core focus at the time. The service ultimately curtailed in popularity as Facebook continued to win markets, including India and Brazil.

4. I believe there was very little connection between orkut.com decline and Google+. By the time Google+ was launched in June 2011, orkut.com was losing ground to Facebook even in Brazil. Facebook overtook orkut.com in Brazil in December 2011, and orkut.com remained online until September 2014, three years after Google+ was launched.

For those curious about technical details:

A. When I became involved in the project, it was because the live service was serving mostly 400 errors and keeling over dead. At the time it was running on Windows and MS-SQL and .NET, the only project of it's kind inside Linux-focused Google. Most of my background is service scalability archicture, so I was asked to get involved to "fix it", I took the team of 5 mostly junior engineers and led the architecture changes to get it serving pages quickly and stop the errors. As I recall, my code-red to fixed the key performance issues took only about a week, after which the massive increase to page performance led to a massive increase in poplarity, causing orkut to shockingly eclipse Google websearch in page views per day not long after.

B. We initially kept the service on .NET technology, both as an experiement within Google, and because I strongly feel the dotnet CLR design (largely due to parametric instantiation and their open-standard model) is the best virtual machine and runtime of it's kind. However, running Windows machines within Google was "not at all straightforward", and it was problematic running on closed source dotnet of the era because we ran into several Microsoft dotnet runtime bugs at scale and had no ability to fix them. We transitioned to using the Mono dotnet runtime on Linux, which was ironically more reliable (and fixable!) and significantly less performant that the Microsoft dotnet runtime for our needs. Eventually the service was transitioned to a Java front-end and C++ backends.

C. Orkut.com images was the first example of Bigtable serving production traffic.

D. We transitioned presentation layer from ASP.NET to Clearsilver templating, developed at my startup Neotonic.com by Brandon Long, and used inside Google for Gmail and other projects. This was for performance, reliability, and to enable the cross platform and cross-language transitions from C# to Java and C++. (Clearsilver was heavily inspired by CS/HDF templating, designed at onelist.com by Scott Shambarger and Ethan Khan) Clearsilver was an unfair weapon in the server-side rendered mostly-static HTML era.

orkut.com is dead, long live orkut.com!

As a Brazilian who used orkut for many years in the 2000s thanks for the fun facts. I used it to keep in touch with my family and friends in Brazil, not many options at the time. Thanks for the service , it was great while it lasted. I think I moved to Facebook in 2010 mostly because I was in Australia and everyone was starting to use Facebook there. Soon after, as you say, most Brazilian moved there as well as orkut became more and more full of spam, emoji vomit and NSFW stuff.