Samsung moved the introducton of the Galaxy S II plus to begin next year.  
SamMobile reported some time ago that we will see the Galaxy S II plus and Galaxy S III Mini before Christmas. Sadly the new information says: GT-I9105 Galaxy S II plus January 28. 
One of the points could be the big succes of the Galaxy S III and Galaxy S II.
Both phones are still selling well even the Galaxy S II price is a little bit higher than before.

SamMobile also reported early some time ago some rumoured specifications of the Galaxy S II plus.
The Galaxy Premiere GT-I9260 and Galaxy S III are still planned for December.
SamMobile was also tipped today about the new GT-I8190 (Golden)

Rumoured specifications GT-I9105 and GT-I9260:
NOTE: the processors looks to be FAKE.

Samsung Galaxy S2 Plus GT-I9105
– 4.3” 480×800(VWGA)sAMOLED+
– MSM7227A-1 Turbo Single 1GHz
– HSDPA 7.2/5.76 900/2100
– EDGE/GPRS 850/900/1800/1900
– 8M (2.0 Mega for VT call)
– 16 GB/32 GB + microSD (up to 32 GB)
– Android 4.0 ICS
– MicroUSB
– 3.5mm Earjack
– BT 2.1
– Wi-Fi 80211 a/b/g/n
– A-GPS
– 1650 mAh
– 125.3×66.1×8.5
– Color:  Blue Grey

Samsung Galaxy Premier GT-I9260
– 4.65” HD
– MSM7227A-1 Turbo Single 1GHz
– HSDPA 7.2/5.76 900/2100
– EDGE/GPRS 850/900/1800/1900
– 8M (2.0 Mega for VT call)
– 8 GB/16 GB + microSD (up to64 GB)
– Jellybean
– MicroUSB
– 3.5mm Earjack
– BT 4.0
– Wi-Fi 80211 a/b/g/n
– A-GPS
– Battery – TBD
– 133.97×68.1×8.8