From the letter (signed by DSCC communications director Eric Schultz):
Dear Governor Palin,
I noticed that you will be in Florida next week to promote your new book Going Rogue. As you know, Florida is home to a competitive Senate race, with either Governor Charlie Crist or former state House Speaker Marco Rubio to face off against Democrat Kendrick Meek. ... I know you are in three Florida cities next week, any of which would be the perfect setting to give your blessing to either Crist or Rubio. With the NY-23 special election over, many are now calling the Florida Republican Senate primary, "the next battle for the heart and soul of the Republican Party." With so much at stake, everyone wants to know - who will you endorse in the Florida Senate race?
Palin is scheduled to hold a three-day swing through Florida on her book tour, starting at a Books-A-Million in Jacksonville on Nov. 24.
Late Update: Crist and Rubio weighed in on the possibility of a Palin endorsement in the race today. Read each candidate's take here.