When incorporating our business, what happens to the software intellectual property we previously created as a team?

Unless you assign and register the ownership of the patent to the corporation, the patent will remain under the ownership of the original applicant(s) (unless your patent was file before Sept. 16, 2012. Before that, it's with the named inventors). It is not unusual for a corporation to be the applicant, separate from the inventors. In this case the corporation owns the patent. Once you are incorporated, assign the patent to the corporation and record it with the USPTO (to give public official notice of assignment). You can find essential information at http://www.uspto.gov/web/offices/pac/mpep/s301.html

IP assets produced through individual or joint-efforts, be they patentable subject matter or protectable under copyright, would by default belong to their inventors and authors. Assignments of those assets can be recorded within the USPTO and Copyright Office, respectively. Now whether it is in your venture's best interest to assign rights to inventions and other work product, versus licensing (exclusively or otherwise), is an open question dependent upon your team members' goals. Further, determining who owns which, or which part of, IP can be a fact-intensive exercise.

It is advisable to engage local IP counsel to appropriately incorporate your venture and allocate any IP rights at issue.

In addition, you need to be clear on what code you have in your asset. Do you have Open Source in your software asset? you should be careful when using OS and use the appropriate license terms when licensing your asset. Watch out with that.