PEAR and PEAR2

Hello!

I am unable to make head or tail of what is actually the difference between
PEAR and PEAR2 and why there are two separate websites. I also had a close
look at the manual but couldn't find anything decent to clarify that
question. Well, PEAR2 is obviously newer than PEAR and probably preferrable
and 'supports' the new features of PHP 5.3, but what does that really mean?
Of course I can use 5.3 stuff also in a PEAR package ... please help!

thanks

Raffael