It's quite possible; looking at FirePython, it can see application logs from GAE applications. It places them into the HTTP response headers, allowing a Javascript client application to see logs from the GAE python application.
Though I haven't tried this, you could use a similar approach to send logs to the Splunk REST API data input endpoint /receivers/simple by using the GAE urlfetch API (google.appengine.api.urlfetch).
You may like to look at the FirePython middleware implementation here for more details about how to get at the log data, and the Splunk REST API documentation about how to format your HTTP requests.
