A few days ago Green Oak released a v2.2 update to members of their Yahoo group, they've now released a public v2.21 update on their website (Though it's labeled as v2.2).

What's new since v2.1:

• Hard sync - The oscillator section of each voice now has a Mogrify control. This parameter will eventually control different things depending on the context, but for this release it controls a hard sync when the wave form type is set to SawSquare or WarmSaw. Hard sync gives the sound a gritty edge. As examples, check out the "Full House" preset in the Vintage section and "Mushroom" in the "Motifs" section.
• Wave shaper - The filter section of each voice now has a Shaper control which imposes a soft wave shaping function on the voice before the filter is applied.
• Reverb - The effects section of Crystal now includes a reverb.
• Patch Bank Browser - The Modulation page now has a patch bank browser, which enables you to browse through saved banks of Crystal patches and import them with the click of a mouse.
• New Richer Sound - Version 2.2 introduces an additional resonant low pass filter which may be used on voices and delays. This filter, called XResLoPass, provides a richer tone for those times when you want that squishy, liquid sound. In addition, SawSquare and WarmSaw oscillators have been enhanced.
• Master Limiter - There is now a master limiter on Crystal's output. This is useful if you get carried away with feedback or resonance parameters and want to avoid blowing out your monitors.
• Resonant high pass filter - The places in Crystal where you can add a filter (the voices and the delays) now have an option for a resonant high pass filter.
• More soundfonts permitted - You can now have up to 1024 soundfonts in the CrystalSoundFonts folder.
• Miscellaneous enhancements.