It depends who's viewing the availability, and for what purpose. It also depends on the likely lengths of any commitments and the sorts of advance planning the client is capable of.
In the application I've inherited, we let people buy individual hours from workers on an ad-hoc basis. Our buyers often have quite short advance planning, so we show them a matrix of individual hours in a week. This fits our users, who typically book one or two hour sessions just a week ahead of time. Unlike your suggestion, however, we don't show the availability of a single worker - rather an aggregate of a pool of potential employees. Historically, our clients would be buying unskilled labour, where employees were interchangeable enough for this to make sense. This has changed, however, and our application may adapt accordingly.
But your users might be different to mine. You might have buyers who aren't looking to get someone in at 4am this Friday - just someone in for a couple of days sometime this month. In which case, you might choose a calendar display, with a low resolution - perhaps individual days of availability.
I wish I could be more specific, but I really couldn't say without knowing the context.