Yes, all bug fixes are in latest 4.1RC1 build.
Memory usage was provided by web server process, it causes some trouble, so we disabled it for now, maybe will be added later.
I noticed the Use Configuration from Previous Build button is greyed out for php 4 and 5 after upgrading to 4.0.10. Is this a bug? I hope it's still saved in a file somewhere.
The new version will save in different format and filename, so your previous build with older version will be gone. You can use the phpinfo to get your current config.
We've been testing with 4.1RC1 for some time and we've just recently come across a problem where PHP files will randomly want to be downloaded instead of being viewed. This could have some serious security implications.