It's still turned off - that initial experiment was averaging 3 MB per
bookmark(!). Getting caching and search working nicely is my big
project for the first week of August. I will roll it out first for
the alpha and beta users (who will get the feature for free), and then
make it available site-wide as part of a paid service. I don't have
the pricing model worked out yet, but you'll be able to apply your
signup fee to the cost.