Spencer from Siliconera.com reports:
"One of the concerns about the spring update was Microsoft enforcing restrictions on Xbox Live Marketplace downloads from other regions.
Once I updated my Xbox 360 with the spring dashboard update I logged on with my Japanese gamertag. To my surprise I still have access to content in that region. I was able to download a game trailer and the demo of Double Dragon without any problems.
Since Japan doesn't have a video marketplace I couldn't test that out, but in the music section songs from Robbie Williams were readily available to purchase.
It looks like video game related content has not been affected by the update (for now?), but what about the video marketplace? If you're in Europe, Canada, or anywhere else that isn't the US do you still have access to US Video Marketplace content?"