Twitter isn't open source either. In that way they are similar to Gmail. Twitter is also headquartered in the US, same as Google. There are innumerable other ways that they are similar.
There are also some major differences, such as the one I described about interoperability. Another difference: unlike Gmail, Twitter's "secret sauce" isn't their website. It's their walled garden social network. Twitter could open source their whole website's code, and it wouldn't much help anyone build a Twitter competitor. StatusNet is already pretty nice.
Also, since we're veering way off topic here, note that I am not arguing that Google is "OSS's best role model", like you said about Twitter. I'm just using Gmail as an example to illustrate how Twitter's walled garden is different than how email works.
There are also some major differences, such as the one I described about interoperability. Another difference: unlike Gmail, Twitter's "secret sauce" isn't their website. It's their walled garden social network. Twitter could open source their whole website's code, and it wouldn't much help anyone build a Twitter competitor. StatusNet is already pretty nice.
Also, since we're veering way off topic here, note that I am not arguing that Google is "OSS's best role model", like you said about Twitter. I'm just using Gmail as an example to illustrate how Twitter's walled garden is different than how email works.