BioMed Central's standard article processing charge (APC) is set to increase from 750 to 850 pounds starting in January 2007. This will cover "the BMC-series of journals and other titles for which peer review is organised in-house". Some "in-house" journals will have higher APCs. The standard APC for "independent" BMC journals will rise to 800 pounds on July 1, 2007 though some of these will have different APCs.
The BMC announcement of this change can be found at http://www.biomedcentral.com/info/about/pr-releases?pr=20061220. Peter Suber has, of course, already noted the change on his fine blog at http://www.earlham.edu/~peters/fos/2006_12_17_fosblogarchive.html#116673666883616482.
I'm not surprised to see these increases. I suspect we'll see similar increases from other publishers. Fortunately, the BMC submission fees are still cheaper than most others.