I’ve found more coverage on Croquet in my rss aggregator, especially on the eLearning blog of Tim Wang.

So, some more facts about Croquet are:

• it’s hard to understand at first, it sems. Wang states that it took him months to understand and appreciate the power behind the system.
•  they’ve shifted from SL to Croquet because of the costs and – much,  much more important – you can import models from tools like Blender, 3d Mx or Maya 3d without problems at all into Croquet! That’s quite an important point where SL still lacks greatly, so this is of course a great plus.
• Croque detects other computers around automatically, that run Croquet, too, and seems to be able to link with them
• It allows appliation sharing between different operating systems.
• Builtin video conferencing and communication tools.
• Other things.

BTW, here is an presentation done by Julian Lombardi about Croquet. Looks interesting to me.