Apple has released the iTunes 10.5 Beta 08 to developers enrolled in Apple's developer program. The iTunes Beta comes without being accompanied by an iOS update which means that iOS 5 Beta 07 will be followed by the Gold Master (GM) release.If you are a registered developer in Apple's standard or enterprise programs, you can download the latest version of iTunes from here. If you are a registered developer, you are required to pay a fee of $99 a year which gives you exclusive access to the latest beta software from Apple.
There doesn't seam to be any major features in this latest update, which probably is aimed at fixing some bugs and improving performance. However it is greatly recommended that you update.
The GM release of iOS and iTunes will be the last update before the software is made available to the public. This update is just a step towards ensuring that Apple has gotten rid of all the bugs before iTunes is ready for public consumption.