OK, looking at that page... The archetecture/chip design can be run at 1ghz - Though TI used a smaller process to reduce power usage.
At the very least, you can get 800mhz safely out of it - the only difference in the omap 34xx series appears to be binning.
Which means what we knew all along: 800mhz is easily possible and will run on -most- n900s. 1ghz is also possible, but requires overvolting in most cases.