The Arch homepage archive shows that the following sentence from the greeting paragraph dates from 2007:
"Please check out our forums and mailing lists to get your feet wet."
I got to thinking that it's probably not ideal to use a colloquial expression in the introductory text. I suspect that most non-native-English-speaking, first-time visitors will land on the English homepage. A good percentage of them are going to attempt a direct translation and then shrug their shoulders (if I may use another idiom to illustrate). Having lived and worked in a non-English speaking country for an extended time, I know how difficult it can be to understand such expressions.
There are many ways the above thought can be conveyed with direct, simple words while maintaining a friendly, welcoming tone. This is not a big deal (yet another idiom!), but I felt it was worth mentioning.
As an ESOL tutor, I know that our inextricable reliance on idioms in the English language can be a barrier to non-native speakers, so I wouldn't see a problem with changing it. I just don't believe, however, that many people (if any) have really gone astray because of it. If "direct translation" is actually something a visitor to archlinux.org tries, then "forums" and "mailing lists" are all they need to be concerned with. If they know what those are, the idiom is inconsequential; if they don't, then it doesn't matter anyway.
A somewhat similar thread: https://bbs.archlinux.org/viewtopic.php?pid=1048357