Until Blast or another Chemist checks in, this is what I found on the web:

It takes a temp of 50°C/120°F to cause Sodium Bicarbonate (Baking Soda) to begin to decompose into Sodium Carbonate and Carbon Dioxide. Higher temps speed the reaction. It's used routinely in cooking as a leavening agent, both from reactions with acidic liquids, and from heat.

While ingesting large amounts can damage the digestive tract, small amounts like in food after cooking are harmless. When you take Sodium Bicarbonate for stomach trouble, the same reaction occurs with stomach acid.

I couldn't find much to indicate that Sodium Carbonate/Soda Ash will corrode metal under normal circumstances, but there were enough warnings about eye contact that I'd be careful when cleaning the residue out of the oven.