(Estimated 40,000 people cross the Bosphorous Bridge to join the protests/OccupyGeziPics)
Taksim Gezi Park in Istanbul is alive with protest at this moment. The action began on May 28, when environmentalists protested plans to remove the park and replace it with a mall, and were met with a brutal police crackdown. Since then thousands have taken to the streets in Istanbul and other Turkish cities (though there's a media blackout on the protests, and poor Internet penetration in Turkey, which means the news is slow to reach other parts of the country).
("Gotta love the creativity of Turkish people clashing with tear gas shot by the police in Istanbul"/@Selintifada)
An excellent summary of the events can be had in the 2013 Taksim Gezi Park protests Wikipedia article. The Occupy Gezi Pics Tumblr is a great clearinghouse of astounding photos from the protests. Here's @MashallahNews's list of English-language tweeters from the protests.
("A protester stands proud after a hard day's night."/OccupyGeziPics)
If you're on the ground in Taksim Gezi, here's a list of nearby WiFi passwords you can use. Reportedly, the local Starbucks is offering shelter, supplies and toilets to demonstrators.
On Twitter, Jacob Appelbaum sends this advice to protesters:
"Photograph radios and communications gear of the police or any other violent thug – what are they using to communicate?"
"Try to use anonymous pre-paid SIM cards and throw away phones; use secure communications software to avoid likely interception."
"Remember that the police and the telecommunications companies will work together to identify every #OccupyGezi person during and afterwards"
"Consider using TextSecure, RedPhone, Orbot, Orweb, Gibberbot and ObscuraCam on Android cell phones; protect yourself!"
"BLACKBERRY IS NOT SECURE! #occupygezi RIM sold out their users and only care about carriers/government "security" concerns."
"The police have detailed location information from cell phones – use burner phones/sim cards; they likely intercept sms/calls."