I'm not sure any book has any momentum. Certainly, some have been discussed more than others but that's only because a few of you have been the most vocal and passionate about them. That's not to diminish the other nominees. I imagine that if a poll was put up, the numbers would surprise us.
Here's what I counted so far in this thread of the number of mentions by posters other than the one nominating the book (multiple mentions by the same poster is counted as one (1) mention):
Doctor Glas - 5 (Libra, Stewart, beergood, saliotthomas, SeoulMan)
Tender is the Night - 5 (Robert, pontalba, Libra, gonewiththewind, silverseason)
Million Little Pieces - 2 (Libra, beergood)
Gone With the Wind - 2 (Peder, Robert)
Last Orders - 2 (Peder, Robert)
Love Medicine - 1 (Peder)
Ironweed - 1 (Silvanous)
My Lobotomy - 1 (Tlou)
Strangers on a Train - 1 (pontalba)
Obviously, the above numbers only reflect what the posting public favors. We can't be sure of the lurkers.