Along with the availability of first Mediatek dual-core MT6577 phones the news of a quad-core successor came up. At first this chipset was said to be released end of 2012 and it went by the name MT6588.
The Amoi N820 (Big V) seems to be the first MTK MT6577 based phone to get an update from ICS to Jelly Bean (Android 4.1). As Amoi most probably did not do all the porting by themselves I am sure MTK will offer this release to other companies, too.
Earlier this year TianYu presented their new K-Touch V8 (Hornet II) phone. The handset was pretty high-end with a 1.5GHz Nvidia Tegra 3 quad-core application processor, 8MP camera and a 4.5″ 1280×720 LCD screen. There has been some rumor that the device should support dual SIM operation.