Yep, you can use query cache from 4.0.1 onwards. Best to read the manual as you will have to configure it for use as well as specify it in the query that you want to cache.
nemonoman, query cache it of great use and value if it fits your db layout and contents
from mysql.com
"Some performance data for the query cache follow. These results were generated by running the MySQL benchmark suite on a Linux Alpha 2 x 500MHz system with 2GB RAM and a 64MB query cache.
* If all the queries you're performing are simple (such as selecting a row from a table with one row), but still differ so that the queries cannot be cached, the overhead for having the query cache active is 13%. This could be regarded as the worst case scenario. In real life, queries tend to be much more complicated, so the overhead normally is significantly lower.
* Searches for a single row in a single-row table are 238% faster with the query cache than without it. This can be regarded as close to the minimum speedup to be expected for a query that is cached. "
Very few tables have only 1 row, and many selects include a join, so cacheing most queries will produce speedups well above the 238%. Not a performance gain to be sniffed at. One of the reasons that mysql queries are so fast would be that many of them are cached, you just don't see it.
