The official announcement :

SVN CLOSED. Playground Repository has been moved to http://code.google.com/p/pcsx2 -- all future updates and commits will be made there instead. :)

Gigaherz said the reasons are :

Look, the merge was decided by both teams. We agreed to join the project because:

1. it will be easier to manage this way
2. the official team wasn't working and so it was pointless to keep it unofficial
3. we felt like it

In case you need some history as to why The Playground version born :

The reason for the project (Playground) was that all of the official developers were busy with real life, so people needed a place to work in (at least temporarily)... and as you can see, as soon as it has become clear that the playground is where the development is taking place, the official team decided to propose merging, and the playground developers gladly accepted to be considered part of the official team.

Sad to see that there will be no more frequent PCSX2 Playground updates but here hoping that their combined focus and effort will make PCSX2 faster and more compatible.