Both algorithms are comparably simple linear classifiers. Given training data in some n-dimensional vector space that is annotated with binary labels the algorithms are guaranteed to find a linear separating hyperplane if one exists. In contrast to the Perceptron, Winnow works only for binary feature vectors.
For more information on the Perceptron see for instance: http://en.wikipedia.org/wiki/Perceptron
Concise course notes on both algorithms: http://pages.cs.wisc.edu/~shuchi/courses/787-F07/scribe-notes/lecture24.pdf
Although the algorithms are comparably simple they still work pretty well for text classification and are fast to train even for huge example sets. In contrast to Naive Bayes they are not based on the assumption that all features (in the domain of text classification: all terms in a document) are independent.
Currently the strategy for parallelisation is simple: Given there is enough training data, split the training data. Train the classifier on each split. The resulting hyperplanes are then averaged.
Currently the patch only contains the code for the classifier itself. It is planned to provide unit tests and at least one example based on the WebKB dataset by the end of November for the serial version. After that the parallelisation will be added.