More to the fire...
I'm relieved it's not just me! Has anyone reported this to Sprint?
I've got a few other things around this to relate:
1. Since the upgrade, I've been getting an error on my primary account under the Sync details. It said something like "Sync is currently experiencing problems. It will be back shortly." An error was usually flagged next to Sync Contacts, but sometimes it would be on Gmail or Calendar as well. I saw a note on another forum to clear the Contacts Storage app from memory to resolve that. Steps below cleared this error, and Primary acct seems to be OK.
2. Under 2.1 I was configured with 3 accounts - my primary (personal Gmail), and two Google Apps domains, one "free" edition for my domain, and one "premier" for work. After the upgrade I couldn't tell that ANY of these were syncing, and my "premier" definitely was NOT. I've gone through some of the steps Gekko mentioned, and haven't been able to resolve the issue.
Here's what I've done. I apologize for the length - just wanted to share some of the steps in case anyone did something slightly different and had success:
1. Removed all secondary accounts, leaving only the primary.
2. Went into Applications->Gmail and removed data, then did Force Stop.
3. Restarted Gmail app.
4. Went into Applications->Contacts Storage and removed data.
5. Went to Accounts and Sync and forced resync of primary account. Contacts did not immediately show up.
6. Rebooted phone (power down, power up). Contacts restored for primary account. Sent a test email to primary account. Notification received instantly, all looks good.
7. Went to Accounts and Sync to add secondary accounts again.
8. Added "free" Apps account. System set up for Sync Contacts and Sync Calendar. Sync Calendar presented the same "Sync is experiencing problems" error. Hit Sync now, error cleared. Sync Gmail did NOT show up in the list.
9. Added "premier" Apps accounts. Contacts and Calendar synced without errors, Sync Gmail did NOT show up in the list.
10. Went to Gmail app. All three accounts show up in the accounts list, but the secondaries show up as "not synced". When you select the account, it says it is not synced and gives instructions to sync (Hit Menu->Refresh to load once, Accounts/Sync to set up sync).
11. Hit Menu->Refresh on premier account. Mail loaded.
12. Sent a test message. No notification, new mail didn't appear in Inbox.
13. Opened a message. Returned to Inbox. No data present, says Loading conversations. After a bit, it loads mail through July 31, but nothing after. Hit Refresh again...new mail loaded, but notifications not working.
14. Went to Accounts/Sync for premier account. Sync Gmail now appears in the list for the secondary accounts, but is unchecked. Checked the box - also checked for Contacts.
15. Repeated above for other secondary account.
16. Cleared all notifications.
17. Sent a test message - no luck.
18. Created a new appointment using desktop for my Premier account - appointment synced to phone almost instantly.
19. Created a new contact using desktop for Premier - contact did NOT sync.
20. Created a new contact using desktop for primary acct - contact synced quickly.
21. Sent another test email to primary - notification on phone right away.
At this point I'm no longer getting sync errors, but sync clearly isn't working properly.