is the data file for tables stored that MySQL uses (with the InnoDB engine); the ib_log....
files are..., well, logs of activity. So, yes, if you're using the InnoDB engine, the do contain (vital) information -- and, if you delete them, well, things won't be good (leave 'em alone).
If you're curious, you can go to http://dev.mysql.com/doc/refman/5.0/en
and search (in the upper right corner of the web page) for "ibdata1" to get a group of MySQL Reference Manual links about ibdata1
Hope this helps some.