The 'TM' means that they are claiming common-law rights in the mark -- the idea is that people will so identify the word 'surface' with Microsoft that it would be unfair to allow anybody else to come out with a 'Surface' tablet.
Microsoft has probably already applied for a registered trademark on the name -- it just takes a few months for those to be published.
Whether the USPTO will let them do this, or not, is another matter. The more generic or descriptive a mark is, the less likely that the USPTO will let it through. So, you cannot trademark the word "apple" when applied to apples, but there's no problem when applied to computers. I don't know that 'surface' really describes this tablet, but it's certainly more descriptive then something fanciful like "Xerox" or "Android." However, note that Microsoft already has a trademark on 'surface' for that table with a display built into it.
'Red Spreadsheet' is nearly complete descriptive -- like the 'apple' above. 'Blue Sky,' on the other hand, is registered to an Arizona real estate company, to a company that does computer animation and to a company that does utility bill management services, among others.