Microsoft announced several improvements to their Live Search Crawler that should significantly improve the efficiency with which MSNbot crawl and index your web sites. MSNbot version 1.1, now supports both HTTP compression and conditional get.
HTTP Compression: HTTP compression allows faster transmission time by compressing static files and application responses, reducing network load between your servers and our crawler. We support the most common compression methods: gzip and deflate as defined by RFC 2616 (see sections 14.11 and 14.39). Compression is currently supported by all major browsers and search engines. Use this online tool to check your server for HTTP compression support.
The following links provide configuration information for IIS, and Apache.
Conditional Get: We support conditional get as defined by RFC 2616 (Section 14.25), generally we will not download the page unless it has changed since the last time we crawled it. As per the standard, our crawler will include the “If-Modified-Since” header & time of last download in the GET request and when available, our crawler will include the “If-None-Match” header and the ETag value in the GET request. If the content hasn't changed the web server will respond with a 304 HTTP response.