Actually Sith, this really doesn't effect the spell at all unless I'm missing some minor nuance that is caused by adding the "personal" wording to the range. If a spells range is "touch" then you simply touch yourself to cast the spell onto your person, like any other touch ranged spell (cure light wounds, etc).
Potions can be made of any spell of 3rd level or lower that targets one or more creatures. There are potions of invis in the DMG and the spell does in fact target one or more creatures, regardless of the "personal" range.
I do see one possible use...
Range: Personal - The spell effects only you.
Range: Touch - You must touch a creature of object in order to affect it.
What if someone casts Hold Person on you and you happen to have Eschew Materials, Still Spell and Silent Spell and mem'd an Invisibility as a 4th level spell (applying the meta-magic feats). You could then (according to the letter of the rules) cast invisibility onto yourself while held, since you don't have to touch yourself. What a stretch! There must be more to it or else it's just a typo.