While everybody is at INTA, OHIM's Department of Industrial Property Policy published the 2009 yearly overview of decisions of the Boards of Appeal, containing references to selected decisions drawn from the almost 1900 cases dealt with by the Boards of Appeal during 2009. It is organised according to legal criteria such as procedural issues or grounds for refusal and should allow the practitioner a quick overview over the burgeoning case law. You can find the PDF here.

This is what the overview has to say about the 2009 case law on absolute grounds for refusal of the registration of single letters as trade marks (bold by Class46):

The Board allowed the registration of the upper case version of the Greek letter omega Ω for ‘soaps, perfumery, essential oils, cosmetics’ in Class 3, as the Board had no evidence that it would be understood by the Greek speaking consumer interested in personal care products as the designation of the size, order number, ingredient, price or any other characteristic of those articles (R1033/2008-1 Ω).

However, the Board rejected the single letter ‘N’ for ‘pressing tools and mechanical pressing apparatus; mechanical pressing apparatus with such pressing tools’ in Class 7 as ‘N’ stands for ‘Newton’, the internationally recognised abbreviation for the physical unit for force. In this case the goods perform a ‘pressing’ function in whose application per instructions force is used and whose performance can be measured in Newtons (R0901/2008-4 ‘N’). The letter ‘E’ was rejected inter alia for ‘plasters of all kinds, wound dressing material, thermometers for medical use and support pants, woven and/or knitted from cellulose for the holding of absorbent pads etc.’ in Classes 5, 10 and 25. The Board considered that the average consumer in the European Union would not assume that the simple letter ‘E’, written in upper or lower case and in any font, is primarily intended to express a link to a particular manufacturer of the goods in question (R0805/2006-1 ‘E’).