In the past, I built RecipeComun using PHP and Java running on top of Quercus inside a Java application server. However, that's a relatively heavy-weight solution.
Now, I would likely build it or something similar with a Ruby on Rails frontend UI. For an initial prototype I would index with SOLR and integrate the two with BlackLight, Solr Flare, or just straight RSolr. For a facet engine on top of Lucene, I think Bobo-Browse from LinkedIn is an interesting alternative to Solr.
Anyone else have different ideas?
Update: I tried installing Ruby/Blacklight on my Windows laptop. I don't recommend this. It needs Linux (for compiling some of the native dependencies used by the ruby libraries). You can work around it with Cygwin with enough effort, I think, but will not be trying.