We recently told you about Protest4, a brand new iPhone and Android app that makes it easy for activists all over the world to connect, communicate and mobilize.

Developed with the Arab uprising and the Occupy Movement in mind, the app has, not surprisingly at all, seen a huge volume of activity in Egypt, among other countries.

It gained 50,000 users in the short space of 17 days, with signups from almost 150 countries worldwide. The most activity has been seen in Pakistan, Egypt and Indonesia.

Protest4 users have come up with creative ways to use the app – most notably in Egypt with about 2,000 users participating in an online discussion campaigning for the release of Egyptian blogger and activist, Alaa Abd El-Fattah who has spent over 2 weeks in prison.

In Pakistan, 15,000 Imran Khan supporters are using the app, while 1,000 anti-Berlusconi activists took to the app calling for the former Italian Prime Minister’s resignation. About 800 users have joined the free West Papua movement, calling for its secession from Indonesia.

It also saw a spike in worldwide activity when the New York Police Department cracked down on the Occupy Movement in Zuccotti Park with global messages of support coming in for the protesters from all over the world.

Protest4′s statistics aren’t all positive. While from day one, trolls had obviously been just as quick to start using the app, Protest4 has come under much more serious attacks. 2 days ago, the app received a denial-of-service attack, but the origin of the attack is unknown. The attack took Protest4′s servers down for several hours.

If you don’t have an iPhone or Android phone, you can still participate in the lively discussions taking place on Protest4 simply by using the app’s web interface.