A couple of hard-working devs over at TabletRoms have been able to squeeze a custom Ice Cream Sandwich/Android 4.0.3 ROM on to the Dell Streak7. Of course they have the usual disclaimer's about being careful not to brick your system. The ROM isn't 100% complete yet, but works pretty well for the most part. They even included a handy breakdown of what works and what doesn't:

What works:
gapps (mostly)
rotation sensors
Screenshots (Press Power + Volume-)
capacitive buttons (home, back, menu)
Video Acceleration
USB Mount
External Storage

What doesn't:

some lag
3g/4g/gsm radio
Bluetooth (until I check with DJ_Steve)
It's great work, so head over to their thread at the source link below to give them some props when you get the chance, as well as read their instructions. Here's a download link for the ROM: Beta3 - ICS-B3.zip

Source: TabletRoms