Those of you who played Platinum before its English release probably remember the patch that allowed for a partial translation floating around the net. It should be possible to do this again for HGSS.
Due to a new tool by loadingNOW, thenewpoketext, the process is actually even easier and better than before. It's as simple as finding which japanese files have already be translated for use in the english versions of DPPt and replacing them with said english version.
Note however that any in-game text that is specific to HGSS can't be translated without a proper translator. An example would be the pokelthon. An example of something that could be translated would be attack and pokemon names.
Just in case there was any doubt, I'm volunteering to do this translation as soon as humanly possible after I get HGSS.
If there is interest it should also be possible to put up HGSS-exclusive text that can't be translated on a webpage somewhere for capable people who are willing to translate. Although I wouldn't advocate a full translation this way it might be nice to play some of the minigames in english... I'll leave that up to the community though.