diff --git a/hyde/ext/publishers/pyfs.py b/hyde/ext/publishers/pyfs.py
index bf64691..9431afb 100644
--- a/hyde/ext/publishers/pyfs.py
+++ b/hyde/ext/publishers/pyfs.py
@@ -1,9 +1,18 @@
 """
 Contains classes and utilities that help publishing a hyde website to
 a filesystem using PyFilesystem FS objects.
+
+This publisher provides an easy way to publish to FTP, SFTP, WebDAV or other
+servers by specifying a PyFS filesystem URL.  For example, the following
+are valid URLs that can be used with this publisher:
+
+    ftp://my.server.com/~username/my_blog/
+    dav:https://username:password@my.server.com/path/to/my/site
+
 """
 
 import getpass
+import hashlib
 
 from hyde.fs import File, Folder
 from hyde.publisher import Publisher
@@ -23,6 +32,10 @@ class PyFS(Publisher):
     def initialize(self, settings):
         self.settings = settings
         self.url = settings.url
+        self.check_mtime = getattr(settings,"check_mtime",False)
+        self.check_etag = getattr(settings,"check_etag",False)
+        if self.check_etag and not isinstance(self.check_etag,basestring):
+            raise ValueError("check_etag must name the etag algorithm")
         self.prompt_for_credentials()
         self.fs = fsopendir(self.url)
 
@@ -39,17 +52,48 @@ class PyFS(Publisher):
     def publish(self):
         super(PyFS, self).publish()
         deploy_fs = OSFS(self.site.config.deploy_root_path.path)
-        for (dirnm,filenms) in deploy_fs.walk():
+        for (dirnm,local_filenms) in deploy_fs.walk():
             logger.info("Making directory: %s",dirnm)
             self.fs.makedir(dirnm,allow_recreate=True)
-            for filenm in filenms:
+            remote_fileinfos = self.fs.listdirinfo(dirnm,files_only=True)
+            #  Process each local file, to see if it needs updating.
+            for filenm in local_filenms:
                 filepath = pathjoin(dirnm,filenm)
+                #  Try to find an existing remote file, to compare metadata.
+                for (nm,info) in remote_fileinfos:
+                    if nm == filenm:
+                        break
+                else:
+                    info = {}
+                #  Skip it if the etags match
+                if self.check_etag and "etag" in info:
+                    with deploy_fs.open(filepath,"rb") as f:
+                        local_etag = self._calculate_etag(f)
+                    if info["etag"] == local_etag:
+                        logger.info("Skipping file [etag]: %s",filepath)
+                        continue
+                #  Skip it if the mtime is more recent remotely.
+                if self.check_mtime and "modified_time" in info:
+                    local_mtime = deploy_fs.getinfo(filepath)["modified_time"]
+                    if info["modified_time"] > local_mtime:
+                        logger.info("Skipping file [mtime]: %s",filepath)
+                        continue
+                #  Upload it to the remote filesystem.
                 logger.info("Uploading file: %s",filepath)
                 with deploy_fs.open(filepath,"rb") as f:
                     self.fs.setcontents(filepath,f)
-            for filenm in self.fs.listdir(dirnm,files_only=True):
+            #  Process each remote file, to see if it needs deleting.
+            for (filenm,info) in remote_fileinfos:
                 filepath = pathjoin(dirnm,filenm)
-                if filenm not in filenms:
+                if filenm not in local_filenms:
                     logger.info("Removing file: %s",filepath)
                     self.fs.remove(filepath)
 
+    def _calculate_etag(self,f):
+        hasher = getattr(hashlib,self.check_etag.lower())()
+        data = f.read(1024*64)
+        while data:
+            hasher.update(data)
+            data = f.read(1024*64)
+        return hasher.hexdigest()
+