Someone around here has talked about a mechanical valve that does just that(it was in one of the discussions about build it yourself). Sorry I don't have time to look. If mechanical is available, it would seem better than electric.
Chris
edit 1
Sorry, I was wrong. The threads talked about detented returns, not auto return(though that was what it was called). Sorry. What is described ought to be available, even if it isn't, though. Good luck.
Chris
edit 2
Ok, this is my last edit. This is the valve I saw. I think the "autocycle" is as you describe.
Chris
Valves: Single Spool Valves
Prince Logsplitter Valves
LS-3000 Valves: These are the popular valves found on many factory-made logsplitters. Pressure actuated detent at “in” position releases when cylinder bottoms out.
Hard chromed spool, adjustable relief, reversible handle. Inlet & outlet 3/4” NPT.
AUTOCYCLE VALVE: Pressure actuated detents at both “in” and “out” positions. Maximum 3000 PSI, 25 GPM. All ports ¾ NPT.
This is a modified 2 spool valve which is used to automatically cycle a hydraulic cylinder (out, back, stop). With the cylinder retracted, both handles are pulled back. The cylinder extends. When it reaches full extension, the first spool will kick to neutral and the cylinder will begin retracting. When it reaches full retraction, the second spool will kick off, and the cycle is complete. To begin the next cycle, both handles are again manually pulled back.
http://www.cylinderservices.net/catalog.asp?prodid=503883