This bug is actually shared across the classic synther and Photosynth 2.
When a description is first typed, prior to upload, all carriage returns|line breaks are stripped out of it when it is saved.
However in Photosynth 2, I find that it seems impossible to save a description with line breaks even after upload and synthing are complete.
This leads to some messy descriptions.
A second quirk I've noticed is that when creating a new synth with Photosynth 2, I am not allowed to paste text into the Title field.
I haven't tested across all browsers to see whether this is universally true yet, though.