Exciting news today. In February I just missed DorkbotPDX's 4 layer panel, but I ordered some 4 layer boards anyway. The boards arrived today, and on first glance they look great.
I thought I'd add some scale, but the only coin I had on me was an obscure coin that doesn't add much scale. I expected HASL finish, but happily discovered that the batch had been upgraded to ENIG. On first inspection, the alignment looks great, holes are centered, contour routing doesn't touch the inner planes. I'll be racing to populate one to test the boards out and put them through the paces. The silkscreen is slightly better than average in resolution and clarity. All told, 3 of these for $16, not bad at all! Can't wait to throw some parts on and fire them up.
I think I will be using this service even more in the future!