Vamm - 9:06 pm on Jul 7, 2010 (gmt 0)
We have about five domains (different everything) of varying size covering various aspects of the same topic and we're getting reasonable success doing interlinking them (as in "mesh").
We doing links in content, like on a site about history of widget X I'd write "the widget X was first used in year 999 and did I mention we have a modern version on sale at our site -url-?".
Also, somehow I got the feeling that multiple smaller sites on multiple domains interlinked this way produce better results than one single domain with a large site. That's probably unless you have a very large site like wikipedia.