This is quite random. I tried to re-subscribe, re-create etc. etc. and I can't see what this is happening. Here on the HubTransport server
[PS] C:\Windows\system32>Start-EdgeSynchronization
RunspaceId : c6286489-790b-44d5-ace5-61a364a5bf6b
Result : Success
Type : Recipients
Name : edge
FailureDetails :
StartUTC : 08/12/2010 01:22:36
EndUTC : 08/12/2010 01:22:39
Added : 0
Deleted : 0
Updated : 0
Scanned : 0
TargetScanned : 0
RunspaceId : c6286489-790b-44d5-ace5-61a364a5bf6b
Result : Success
Type : Configuration
Name : edge
FailureDetails :
StartUTC : 08/12/2010 01:22:36
EndUTC : 08/12/2010 01:22:39
Added : 0
Deleted : 0
Updated : 0
Scanned : 0
TargetScanned : 0
Looks good. Now a normal test
[PS] C:\Windows\system32>Test-EdgeSynchronization
RunspaceId : c6286489-790b-44d5-ace5-61a364a5bf6b
SyncStatus : Normal
UtcNow : 08/12/2010 01:24:46
Name : edge
LeaseHolder : CN=MAIL,CN=Servers,CN=Exchange Admin
LeaseType : Option
FailureDetail :
LeaseExpiryUtc : 08/12/2010 01:52:39
LastSynchronizedUtc : 08/12/2010 01:22:39
TransportServerStatus : Skipped
TransportConfigStatus : Skipped
AcceptedDomainStatus : Skipped
RemoteDomainStatus : Skipped
SendConnectorStatus : Skipped
MessageClassificationStatus : Skipped
RecipientStatus : Skipped
CredentialRecords : Number of credentials 3
CookieRecords : Number of cookies 2
Looks good too. But testing a specific mailbox gives me the 'inconclusive' error
[PS] C:\Windows\system32>Test-EdgeSynchronization -VerifyRecipient xxx@xxx.com
RunspaceId : c6286489-790b-44d5-ace5-61a364a5bf6b
[B][color=red]SyncStatus : Inconclusive[/color][/B]
UtcNow : 08/12/2010 01:25:37
Name : edge
LeaseHolder : CN=MAIL,CN=Servers,CN=Exchange Administrative Group
LeaseType : Option
FailureDetail :
LeaseExpiryUtc : 08/12/2010 01:52:39
LastSynchronizedUtc : 08/12/2010 01:22:39
TransportServerStatus : Skipped
TransportConfigStatus : Skipped
AcceptedDomainStatus : Skipped
RemoteDomainStatus : Skipped
SendConnectorStatus : Skipped
MessageClassificationStatus : Skipped
RecipientStatus : Synchronized
CredentialRecords : Number of credentials 3
CookieRecords : Number of cookies 2
The only two hits on google was to either re-subscribe (done that) and also missing product keys (all fully licensed). Even the Eventlog is as clean as you want it to be

(LeaseHolder lines have been shortened on purpose)