Hi Jeff,
Upgrades will be annual and in line with major product releases. This means that if you purchase a company seat license now, then you can expect to spend about 50% of $289 ($144.50) late in 2013 if you want to upgrade to NCrunch V2.
Upgrades are not compulsory. V1 licenses will continue to work perpetually without expiry, so the main motives for upgrading will likely be if you want to make use of new V2 features, or if a new version of Visual Studio is released (i.e. 2014) and you want to upgrade to it.
I hope this makes sense. Do let me know if you need any more info.
Cheers,
Remco