Edit: Now I see there is a post just following yours that includes this entire thread that this code came from. Check it out.
This code came from J Barrette of ESRI on another Forum post. It exports bookmarks to jpg files but with some tweaking you might be able to get it to do what you want. But it may only be available in 10.1?
import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Transportation")[0]
for bkmk in arcpy.mapping.ListBookmarks(mxd, data_frame=df):
df.extent = bkmk.extent
outFile = r"C:\Project\Output\\" + bkmk.name + ".jpg"
arcpy.mapping.ExportToJPEG(mxd, outFile, df)
del mxd