In addition to initial deployments, WebMatrix also supports incremental file updates on subsequent publishes.  Make a change to a local file, click the Publish button again, and WebMatrix will calculate the differences between your local site and your published one and only transfer the files that have been modified (notice that the database by default will not be redeployed to avoid overwriting any data on the remote host):

Clicking the “continue” button above will only transfer the one modified file.  This makes updating even large sites easy and fast.