Does anybody know anything about chrome.experimental.sidebar namespace? Is it still available? Is it going to be removed? Anything?
It's not available in the Google Chrome Extensions documentation anymore.
Do you know anything about availability of sidebars in Google Chrome?
You can see all relevant information in the corresponding Chrome bug. To quote comment 41:
The sidebar's on ice for now. We're going to go through an API prioritization exercise near the end of the year to figure out what's important for 2012, so there's some chance it could resurface. I'd put the probability pretty low though.
And comment 42 clarifies that a sidebar API doesn't seem to be the top priority right now but it might still get finished later. Or, what sounds more likely judging by comment 50, this functionality will be morphed into a more generic API.