You can now download the v1.04 update for all Authorized Steinway & Sons editions at garritan.com. Basic users can save time by downloading the update zip file rather than the full product zip.
Changes include:

• Improved Sustain Resonance compatibility with plugin hosts, improved sustain resonance CPU efficiency particularly with small audio device buffer sizes, sustain resonance bug fix for sample rates of 88,96,176, and 192khz.
• Improved host (sequencers/notation) compatibility.
• Bug fix of the tuning type’s display – it now correctly shows the current temperament.
• Improvements to polyphony and voice stealing.
• Improved Snow Leopard compatibility.
• Minor UI issues fixed.

For the future, version 1.05 is under development, which I currently expect will include pedaling fixes and pro/standard voicing improvements. Also, the Steinway B from Skywalker Sound is under development, although it’s a different product.