>>>I didn't look too close yet, but looks like there is an extra comma at the end of cmd line - not sure how did it get there.
>>
>>Right, I took out the extra commas, and it saved successfully, but when I tried to run it, I get this:
>>
>>Must declare the scalar variable "@StartDate".
>
>Getting this error right now - give me a sec.

Of course!!!

Here is the correct version

alter PROCEDURE [dbo].[GetWellData] 
	-- Add the parameters for the stored procedure here	
	@Tablename sysname,	 
	@StartDate datetime,
	@EndDate datetime
AS
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from interfering with SELECT statements.
	SET NOCOUNT ON;
	SET @TableName = RTRIM(@TableName)

	Declare @cmd AS NVARCHAR(max)
   DECLARE @ParmDefinition NVARCHAR(500)
   SET @ParmDefinition = N'@InnerStartDate datetime ,@InnerEndDate datetime'

	SET @cmd = N'Select top 10 * from ' + QUOTENAME(@TableName) + ' where BidDateTime between @InnerStartDate and @InnerEndDate'
    
	exec sp_executesql @cmd, @ParmDefinition,
            @InnerStartDate = @StartDate,
            @InnerEndDate  = @EndDate
END
go

execute GetWellData 'Bid', '20080801','20091101'