For a while there it the only new rims coming out were Disc-specific,
thanks to Pacenti.

Chris just announced the details of their new polished 650b rims
planned for October:
http://velo-orange.blogspot.com/2009/07/more-on-new-rims-and-wheels.html

The CTA in Australia is offering polished rims again. They have the
widespread Synergy, but also an Aerohead I haven't seen anywhere else.
Their Aerohead might be a bit stouter than the super-light 700c
version, as it's only 5g lighter (whereas the other 584 offerings are
25-30g lighter than their 622 counterparts)
http://www.chainringtransitauthority.com/store/650b/650b_rims.shtml

While looking around I noticed that Velocity is making a 650b Dyad,
but it isn't in their catalog and mostly only pops up on machine-built
wheels:
http://www.ebikestop.com/velocity_dyad_650b_32h_silver_with_msw-RM4516.php

The Weinmann ZAC 19 is supposed to be a replacement for the Rigida
Sphinx, though it may be disappearing too:
http://www.melpintoimports.com/rims/touring650b.html