Year-to-Date (2009), out of 16 single family home sales in Arlington, the average original list price to sale price is $589,225 - $534,844. A 93% ratio between original list price to sale price. The average listing price when a home sells compared to its average sale price is $559,919 - $524,844. As you can see, most home go through a price reduction prior to selling and the average.
Last year, at this time, there were also 16 homes sales. The average original listing price was $539,481 compared to an average sale price of $520,388, which is a ratio of 97%. The average listing price when those homes were sold was $523,794.
Single family homes sales have slightly appreciated at this point in time, compared to last year, by $14,456. I hope that this helps to answer your questions and I'd be happy to go over the number further with you if you are interested.