The spin GM used when describing the lack of a V8 in the HUMMER H3 was that the 220 hp inline 5 cylinder engine would be tuned to get performance as good as the H2 while getting a whopping (for a HUMMER, anyway) 20 mpg.
Now, according to Automotive News, it looks like both a V8 and a diesel engine are in the works for a few years down the road. AN quoted two sources within GM who asked not to be named, so we'll see if this holds true or not.
The same article also recounts a speech given to HUMMER dealers at the Dealer Business Conference last week in Las Vegas, in which GM told dealers that HUMMER will build 150 special editions that offer more "bling" than current models. Among the special features are Fusion Orange or Pacific Blue paint and rear-view cameras to counter the blind spot problem present in the H2. The special edition H2s are slated for first quarter of 2006.