That's looks like one of ours - even though I can't say for sure as IP does not seem to match exactly, I will need to see bots request for robots.txt to be sure.
If you was to stop it crawling your site then all you need to do is to add it to robots.txt:
If you want extra protection I can add it to a special no-crawl list, we can discuss it via sticky if you want.
Blocking by IP is not a smart move and generally blocking by HTACCESS bots that support robots.txt is not very smart either - at the very least allow robots.txt to be taken for the block to be efficiently implemented.
We indeed had a problem with fake bots pretending to be us - however this situation seems to have stopped in late January 2008 and I have not had any fake bot reports since then.
So, to reiterate - we obey robots.txt, this includes Crawl-Delay param that can help slow down crawling, also new bot that is being beta tested now supports GZIP to reduce bandwidth usage on sites, if you want to block us please please please use roborts.txt - this will be best for you and us.
Edit - Receptional Andy: we have released big index last month that I think is beneficial to site owners, I can't post much about it here though, but those who seek shall find.
[edited by: Lord_Majestic at 8:04 pm (utc) on Mar. 18, 2008]