[TYPO3] any recommendation on php version?

[Katja Lampela]

Hi all,
I have on my system php version 5.1.6 and mysql 5.0.27. I'm planning on 
some update and was wondering if there were any recommendations on 
current versions.

Since this is a production virtual server, I'm wondering also could 
there be some problems anticipated upgrading for example 5.1.6 -> 5.2..?

I'm also very interested to hear, if you have any "non-recommendations" 
- that is versions which you have found problems on working with TYPO3.

Cheers!
- Katja