I just attended MySQL webinar "What's New: MySQL 5.5 and MySQL Enterprise Edition". You may find the recording of this webinar at mysql.com. It was nice to see improved InnoDB performance (10x) as compared to MySQL 5.1 InnoDB. A couple of people in the webinar reported that they have experienced the enhanced performance with MySQL 5.5.

Here are some of the questions that looked interesting to me

Q: you have comparion charts between myisam and innodb?
A: We've just completed our MyISAM and InnoDB benchmarking and will be posting a whitepaper this week.

Q: Can you compare MySQL 5.5 partitioning schemas and performance with MS SQL Server 2008?
A: I'd recommend the following whitepaper for details: http://www.mysql.com/why-mysql/white-papers/mysql_wp_partitioning.php

Q: Are there any linux graphs/stats with using 2 or 4 core CPU's? The previous linux graphs were with 6 cores.
A: Here is a link to additional details regarding some of the benchmarks. Many of them start w/ 4 cores enabled and then expand to additional cores. As 2 cores scaled well with previous version, I believe most benchmarks started with 4 cores: http://assets.en.oreilly.com/1/event/36/What_s New in MySQL 5_5__ Performance and Scalability Benchmarks Presentation.pdf

Q: The white paper referenced for partitions is for 5.1. I am interested in the features and extensions that have been implemented in 5.5 A. Is there a newer white paper? Thanks
Q: Yes -- Here are improvements for 5.5 regarding partitioning http://dev.mysql.com/tech-resources/articles/mysql_55_partitioning.html

Q: Does MySQL support sub-partitioning ?
A: Yes http://dev.mysql.com/doc/refman/5.5/en/partitioning-subpartitions.html

Q: Is there any testing data available that focuses on the improved innodb performance in a virtual/cloud environment rather then the larger multi-core physical testing platforms noted in the presentation
A: I'd recommend reviewing the detailed presentation posted from our users conf: http://www.mysql.com/news-and-events/on-demand-webinars/display-od-532.html