This could be an elaborate hoax by Huk and the owner of the raptor account, but there are some evidence that this is likely fOrGG. fOrGG announced his retirement on December 28th, 2010. The raptor account was initially placed into gold on January 8th, 2011 according to sc2ranks.com:
It has also previously been mentioned in another stream chat that Raptor is a former SC1 progamer. I did not save a copy of that stream chat, but it was on either San's stream or ZeNEXTandongho (I don't really remember) and by the streamer himself or someone helping him set up who definitely seemed certain.
Obviously this does not clear up whether he plans to take up sc2 progaming or whether it is just a hobby. However this season he had over 1200 games played which is higher than the vast majority of the Korean GM league (these figures may be skewed slightly as progamers in team houses likely do a larger amount of customs). This suggests he is at least taking it seriously.
I'm not sure whether fOrGG really understood that Huk was streaming and therefore was a bit hestitant about making this topic, but either way Huk had 5000+ viewers and some discussion about it in the Huk streamchat has now been linked on reddit so I figured it's already out there and we may as well have a discussion thread here on TL. Either way I don't see how it could really hurt fOrGG.
The relevant game can be found in the VOD:
http://www.justin.tv/liquidhuk/b/290221945
It is at the end of part 2 and goes on in part 3 (starts at about 1:57:20 in part 2).
EDIT: Apparently many sc2 players do not know forgg. He was a very strong bw player playing on kt with flash for the last part of his career, but originally on oz. In 2008 he won the Arena MSL beating Jaedong 3-0 and Flash 3-1. Beating Jaedong 3-0 in a bo5 in 2008 was a ridiculous feat.
Later on he fell into somewhat of a slump, but remained a regular in proleague (unlike b-teamers like MC). However he was to some extent overshadowed by flash and never really recovered his 2008 form. At the end of 2010 he announced his retirement.
He is likely the strongest bw player to switch over if he will compete professionally. Of course Nada, Boxer and July are more accomplished, but in modern BW forgg was much better than such players.
Also he was famous for his timing attacks (which caused the nicknames you see people call him in this thread).
Some people seem to downplay forgg's recent skill a bit so some comparison to current sc2 players is needed. To be fielded regularly in the proleague (BW teamleague) you had to be quite good.
The following is the win-loss (ratio) statistics for some of the current sc2 stars and forgg.
In the 2009-2010 proleague:
MC (Iron): 0-2 (0%)
Sangho: 3-7 (30%)
MVP: 5-12 (29.4%)
forgg: 10-10 (50%)
Nestea (zergbong): 0-0 (not fielded)
Puma: 3-9 (25%)
In the 2008-2009 proleague:
MC (Iron): 1-2 (33.3%)
Sangho: 23-15 (60.5%)
MVP: 5-15 (25%)
Nestea (zergbong): 0-1 (0%)
forgg: 14-10 (58.3%)
Puma: 1-6 (14.3%)
Individual league stats are not really reliable as when you get far you play better players and total stats are not better as "bad" players compete in the minor leagues which are not as good.