We released a new version of the Wave sandbox server (wavesandbox.com) today, primarily to resolve the issue with robots not being able to create blips. We expect to release a new version of the Wave preview server (wave.google.com) within the week.
Those changes are also documented in the changelog:
http://code.google.com/p/google-wave-resources/wiki/WaveAPIsChangeLog
If you find a regression bug, please report it in the issue tracker if others confirm your suspicions.
Thanks!
- pamela