A 126-megabyte download of the source code for AT&T’s variant of the Samsung Galaxy S II is now available from the Samsung Open Source Release Center (OSRC). Samsung released the said source code for the device long before the handset has even been released on AT&T, presumably to give software engineers and enthusiasts a headstart with tweaking the code.

AT&T is expected to make its Samsung Galaxy S II variant available starting October 2 for US$200 (with two-year contract).

With the source code for the handset available to the public, hackers and modders can examine the source code and contribute fixes for bugs, and can tweak the code to add/remove existing functionality or improve the device’s performance (e.g., scale up the processor speed to 1.8 GHz).

AT&T’s variant of the Galaxy S II remains true to the screen size of the international version of the Samsung Galaxy S II. The variants for T-Mobile (said to be called the Samsung Hercules) and Sprint (rebranded into the Samsung Epic 4G Touch) both have slightly bigger screens at 4.52 inches.

All three variants were just recently launched in the United States. Sprint has already released its variant, while T-Mobile’s Samsung Hercules release date has been rumored for October 26, although other reports suggest it could come earlier on October 15.

Samsung had also previously released the source code for the international version of the Samsung Galaxy S II and the Samsung Epic 4G Touch.

With the Galaxy S II’s source code at your fingertips, what improvements do you intend to work into it?