While I don't recommend you rush out and deploy this to your production instances today, it might not be a bad idea to get a head start on testing the fixes in SQL Server 2008 SP2 in your development and/or test environments. I have tested it on a few standalone machines, and so far have not come across any issues. I have not yet attempted to install it on any clusters.
You can download the CTP here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=65606fdd-093f-4c70-91f6-dc1f24520e8f
If you want the Express Editions, go here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=c56e753d-13ef-4b95-a5eb-0b470bf56341
You can read about what's fixed in KB #979450:
http://support.microsoft.com/?kbid=979450
This will put you at build 10.0.3798.0. While the list of fixes for the SP2 CTP itself is small, you should also consider what build you're at now. Most of the fixes from cumulative updates released after SP1 will also be included (and I think this is part of the reason the CU releases got out of sync last month; potentially they are trying to avoid the "SP removes fixes from the most recent CU" problem that we've seen in the past). Here is the list:
SQL Server 2008 SP1 Cumulative Update #8 (10.0.2775): http://support.microsoft.com/?kbid=981702
SQL Server 2008 SP1 Cumulative Update #7 (10.0.2766): http://support.microsoft.com/?kbid=979065
SQL Server 2008 SP1 Cumulative Update #6 (10.0.2757): http://support.microsoft.com/?kbid=977443
SQL Server 2008 SP1 Cumulative Update #5 (10.0.2746): http://support.microsoft.com/?kbid=975977
SQL Server 2008 SP1 Cumulative Update #4 (10.0.2734): http://support.microsoft.com/?kbid=973602
SQL Server 2008 SP1 Cumulative Update #3 (10.0.2723): http://support.microsoft.com/?kbid=971491
SQL Server 2008 SP1 Cumulative Update #2 (10.0.2714): http://support.microsoft.com/?kbid=970315
SQL Server 2008 SP1 Cumulative Update #1 (10.0.2710): http://support.microsoft.com/?kbid=969099
And if you're not even on SP1 yet, I'd love to know what you're waiting for...
You should also note that SP2 brings support for Data-Tier Applications, the SQL Server Utility, and a SharePoint add-in.