Tipfy 1.0b1 already uses thread-local for global variables (app and
request), so it is already thread-safe. This was done when we started
to support running tipfy outside of App Engine, similarly to what was
done in webapp2 (I ported the same werkzeug thread-local utilities to
webapp2). As far as I know, everything else is thread safe (one
exception, *maybe*: I need to review i18n and backport what was done
in webapp2).
-- rodrigo