If you're a tweak developer applying for a software engineering (or related) job, here's some advice about how to present and use your tweak development experience to help you get a job that you want.
It's pretty common for independent tweak development to be a person's first professional-level software development experience, and it can be quite impressive to potential employers that you've researched, developed, published, and supported your own products.
Working on your resume
Wondering what to put on your resume for your tweak development experience? "Independent software developer" is totally fine as a job title. In general, you can use "extensions" as a more formal way of saying "tweaks". You can say something like "Independent runtime modifications developer" as a more technical phrase.
You can talk about how you did reverse engineering, development, and marketing/support for extensions that added new features to an operating system - and note the number of people who purchased and/or used them. It can be really great to point out the part where you had to do independent research and reverse engineering on a closed operating system - a lot of developers don't have this kind of creative research skill.
You can say that your work was distributed via (or published on) Cydia, and you can describe it as "a popular software marketplace for jailbroken iOS devices". If you don't want to mention "jailbreaking", you can just say "Cydia", although many software companies understand what jailbreaking is and that it isn't bad.
Be specific about the frameworks and APIs you had to reverse and what you were able to achieve, especially for an iOS-related job!
If you'd like to get feedback on your resume or on a job application relevant to iOS development, the people of the #iphonedev and #theos IRC channels may be willing to check it out for you and make suggestions.
People and companies that might want to hire you
Tweak developers have used their experience to help them build their own companies together, get internships and jobs at prestigious companies like Facebook and Apple, build companies that got acquired by Google, and more. An App Store app built by former tweak developers has even received an Apple Design Award.
If you're looking for a software engineering job, especially one in the Bay Area, you can ask around (such as in the #iphonedev and #theos IRC channels) - there are a lot of potential connections in the community to people working at companies that might want to hire you.
Feel free to list yourself here with contact info if you work at a company that might want to hire people with tweak development experience.
Most interviewers aren't familiar with the specifics of jailbreaking, and might only know about it in broad terms if they've even heard of it at all. This means it's important to phrase your work with jailbreaking in terms that are easy for anyone to understand, and emphasize that the skills you've learned from tweak development are useful in many other fields as well.
Examples of good skills to highlight include reverse engineering, collaboration with other developers, maintaining clean and readable code, and working in a customer support role. You can also talk about how you made tweaks usable and well integrated into iOS through good design and user experience practices.
It can be helpful to have a jailbroken device (or at least screenshots) with you for interviews so you can demonstrate your tweaks to interviewers. Showing off a tweak you've made and talking the interviewer through the process you used to develop it gives them insight into what you know and how that knowledge can be applied to the position you're interviewing for.