If you are looking to store web logs and then do ad hoc queries you might/should be using Hadoop (depending on how big your logs are)
 
I agree, take a look at the Cloudera Hadopp 3 CDH3, they include an app called Flume for moving data...

"As a result, we designed and built Flume. Flume is a distributed service that makes it very easy to collect and aggregate your data into a persistent store such as HDFS. Flume can read data from almost any source log files, Syslog packets, the standard output of any Unix process and can deliver it to a batch processing system like Hadoop or a real-time data store like HBase. All this can be configured dynamically from a single, central location no more tedious configuration file editing and process restarting. Flume will collect the data from wherever existing applications are storing it, and whisk it away for further analysis and processing."

(I wonder if this could deliver into Cassanda :) )

If it's straight log file processing Hadoop may be a better fit.

Aaron