Yes. There is more information in the version updates forum, especially about using php5 as cgi so you can run both versions of php without causing apache to fail.
MySQL 4.1.x is certainly no problem and you should be able to upgrade with no trouble that I can think of. But be warned, I noticed a thread in the version updates forum that it could cause problems with applications such as phpbb although it hasn't been confirmed or denied yet, I would keep my eyes open and personally probably won't begin updating systems to it until bug (if any) have been worked out.