The Yalkut Shimoni (Braishis 152) sees the tears shed by Yosef and Binyamin when Yosef reveals himself to his brothers as an allusion to tears of grief for the destruction of the Mishkan and Beis haMikdash. Yosef cried to his brothers as well -- "vayitein es kolo b'bechi" -- as a means of comforting them. The Yalkut concludes that Yosef's tears of comfort portend the tears which with bring about the future redemption, as Yirmiyahu haNavi says, "b'bechi yavo'u" (Yir. 31:8).
Chazal tell us that the seeds of exile were planted when the Jewish people cried upon hearing the report of the spies. Because we cried needlessly, for a lack of bitachon that we could conquer Eretz Yisrael, we were punished and given a reason to cry.
Perhaps galus and geulah are all about why we cry and what we cry for. I would like to suggest that the tears of our matriarch Rachel (also in Yir. 31) which we mentioned yesterday are not simply an expression of grief, but as tears shed for the right reason, tears shed for love of Eretz Yisrael and for love of the Jewish people who are suffering, they serve as an instrument to bringing is closer to geulah.
The gemara (Brachos 32b) relates that after the destruction of the Beis haMikdash all the gates of prayer to Heaven have been closed with the exception of one -- the gate of tears.