In Silicon Valley, there are few developers more respected than Joe Hewitt — he helped create Firefox, he built the indispensible development tool FireBug, and he was also responsible for both Facebook’s ‘Touch’ mobile website and the first few versions of its incredibly popular native iPhone application (which he’s rumored to have built singlehandedly). And Hewitt, who is still a prominent Facebook employee, isn’t shy about voicing his opinions when it comes to technology.

Update: Hewitt has written a blog post clarifying his stance.

This evening Hewitt has tweeted an hour-long stream of criticism directed at Google’s definition of “Open” when it comes to Android — a topic that was brought up by Steve Jobs during his tirade against Google during Apple’s earnings call yesterday. Android chief Andy Rubin responded to Jobs with his first tweet, which contained his definition of open: a terminal command that can be used to download the source code of the current version of Android. But Hewitt obviously isn’t satisfied.

Hewitt kicked off his series of tweets with a question: “How does Android get away with the “open” claim when the source isn’t public until major releases, and no one outside Google can check in?”

For those who aren’t familiar with Android’s release cycle, Hewitt is referring to the fact that developers can’t take a look at the current version of the OS as it’s being developed. Instead, they have to wait for the Android team to finish the latest release internally, at which point Google releases the code to developers (and carriers begin to deploy it to handsets a few weeks later). This process stands in contrast with many other popular projects that are considered to be ‘Open’, which allow developers to access the code as it’s being written, and in some cases, to check new code in themselves.

After that initial tweet, Hewitt continued to explain his argument (in some cases through replies to other users on Twitter). Here are some of the key tweets, you can read his full tweet stream here:

Compare the Android “open source” model to Firefox or Linux if you want to see how disingenuous that “open” claim is.

Until Android is read/write open, it’s no different than iOS to me. Open source means sharing control with the community, not show and tell.

I think it is the lack of visibility into daily progress that bothers me about Android more than the lack of write access.

Refusing to share your vision and progress until the big event… how very open.

@mclazarus true open source projects have a process for earning checkin privileges.

Point I am trying to make is, Rubin bickering with Jobs is a farce, because both refuse to share the one thing that matters: control.

@risaacs99 I am saying they are doing the bare minimum, but boasting as if they are on the level of Linux or Firefox, or even Chrome OS.

@risaacs99 like Rubin bragging about how downloading a months old code dump is the definition of open.

It’s obviously Google’s prerogative to decide what it wants to do with Android’s code. Hewitt’s point, it seems, is that Google’s definition of “Open” in this case is very different from the openness seen in Firefox and Chrome, but it’s reaping the same PR benefits. And while I’d personally consider Android to fall solidly in the ‘Open’ spectrum — you can fork it and install it on whatever device you can get it running on, which can’t be said about iOS — there’s no doubt that the meaning of the word has become very vague (or meaningless, depending on who you ask).

One other thing to note: Hewitt has had a lot to say about Android over the last several months. It’s my guess that he’s playing a key role in the customized version of Android that Facebook is probably developing, which could explain why he’d like access to code from a future release.