given that unlabeled samples are far more abundant than labeled samples

It is also related to Transfer learning. This paper provides a good background http://www.stanford.edu/~hllee/icml07-selftaughtlearning.pdf

It contains a nice graphic describing difference between Supervised, Semi-Supervised, Transfer and Self-Taught learning.

Since twitter data consists of short texts. Unlabeled data from sources other than twitter could also be used, e.g. Google Buzz.