Do you remember at school, when the teachers mentioned that something would be on your "permanent record"? The big secret is that there isn't one. Apologies to all teachers, but it's not likely this blog's demographic will reach your students. However, since the advent of the internet, a permanent record does exist. Everywhere from the Wayback Machine to Google's cache contains copies of all public activity you post online.
At Collabora, we hire some of the best open source software engineers to work for our clients. It should be no surprise that a quick Ohloh and search for someone's name is a standard part of the hiring process. This normally comes up with all sorts of exciting things which people have done, both with software and further abroad.
A tricky situation will occur if you have lost your temper online, as Patrick Ryan has done recently. He made a comment on #node.js on the Freenode network that:
[20.16.34] < TheEmpath> anyone else have a hot programmer girl in their office? o____O
This was quite rightly called out as being inappropriate for the channel, and quickly decided to have a large and abusive rant about this. This was then continued with him opening a number of bugs against the projects owned by the person who called him out, with titles such as "Hyperactive Leftist Power Trip not included" and "Not anti-Republican enough".
This then gets worse. Once the log is posted (link above) there is yet more abuse and unfounded accusations by Mr Ryan in the comments.
So, what happens when you search for his name? You get a log with someone being entirely inappropriate and then large rants. Not the best move for a software consultant.