Since the roadmap only shows PR ratings, it's impossible to tell what clock speeds the chips are running at. It does appear that Athlon64 processors with 1MB of L2 will get as little as 200 and as many as 500 extra + points than Athlon64s with 256KB of L2, but that's just speculation based on what's in the roadmap.
My hope is that AMD makes the methods it uses to determine Hammer's PR scale readily available when the processor is eventually released. It makes little sense to keep Hammer indexed against the now ancient Thunderbird core, especially considering Hammer's 64-bit capabilities. It seems to me that Hammer's PR ratings would have to be based on 32-bit application performance in a 32-bit operating system, since any index processor (Athlon XPs included) can't deal with 64-bits. Such a rating system could sell Hammer's potentially better 64-bit performance short, which makes me wonder if AMD will tack on a few extra + points to indicate the processor's potential for better performance with software compiled to take advantage of the extra 32-bits.
Either way, PR ratings look like they'll be a headache to decipher this year. Last year, we only had to worry about clock speeds contributing to the scale. Now, it looks like we''ll have to deal with cache size and perhaps even "64-bitness" playing a role.