SUN acquired MySQL and there is a price for it. Nothing what is free is really free…
Jeremy Cole in his blog discussed and got some clarification about changes in the MySQL development/release/contribution policies introduced by SUN.
MySQL will start offering some features (specifically ones related to online backups) only in MySQL Enterprise. This represents a substantive change to their development model — previously they have been developing features in both MySQL Community and MySQL Enterprise. However, with a shift to offering some features only in MySQL Enterprise, this means a shift to development of those features occurring (and thus code being tested) only in MySQL Enterprise.
Also check reply by Marten Mickos which acknowledges and extrapolates about this change.
No free cheese anymore? Not that it was free (people have contributed their time), but it was available for free. I would suspect that new features available in enterprise (read “commercial”) edition would be prohibited to be reintroduced in the free version.
Otherwise you are to pay some $595 a year for Enterprise Edition.