TeX Live 2011 is available online now. It will be sent on DVD to members of most TeX user groups later this summer (barring unknowable production and mailing delays).
You can acquire TeX Live in many ways. For typical use, we recommend the first two:
The last general update of packages and programs for the 2011 DVD was made on 28 June 2011. However, we will be continuously updating packages in TL as they are released to CTAN. Post-installation updates are done with the tlmgr program. tlmgr also provides many other TeX installation options and features, explained in the tlmgr documentation.
Although it is possible to update continuously, it is not necessary or even recommended. The set of packages and programs that were included in the official release will most likely suffice unless you know you specifically need updates made since then. That set is also the only one which gets tested as a coherent release.
Older releases of TeX Live are available for historical purposes.