108 is Aaron....Wallace by Josh

Everyone wonders who 108 is on Jacob's lighthouse dial? Who is 'Wallace'?

Whose last names don't we know or are suspect? A few, but most are on island.

We've never discovered Claire's boyfriend (and Aaron's dad)'s last name.

Her boyfriend, the painter, 'Thomas'....could certainly have the last name Wallace. Making Aaron Wallace the important figure that Jacob was guiding back to the island.

Aaron is definitely important enough to draw back, given the volume of screen time devoted to him this season (and throughout the series). He is also the next generation of the seemingly powerful Shephard family bloodline. He was also protected by many characters associated with Jacob and the island along the way, snatched from Claire for protection from her insanity or other threats and even one of the rare few allowed to leave the island and remain 'gone' (Walt, too).

Jacob sees that now is the time to cash in on the secret weapon he has been protecting. 'Candidate' Aaron can arrive on the island just in time while his enemy (MIB) is not even looking for this unknown candidate.

The smashing of the glass will simply cause new events to direct him there, as Jacob confidently explained to Hurley. This also explains his comment "They'll find another way" as it is unlikely for Aaron to arriving unaccompanied (maybe Desmond?).