Ask HN: What kind of immigration challenges do startups face?

I know immigrants are heavily represented in startup circles, and that this leads to a lot of interaction with US immigration authorities for startups.

There's the obvious H1B application process that I'm sure many of us have been through, but I'm sure that's only the beginning of the process. What else has to be done from an immigration standpoint to ensure sure that employees are able to continue being productive for their companies?